scholarly journals SUMOylation of the MAGUK protein CASK regulates dendritic spinogenesis

2008 ◽  
Vol 182 (1) ◽  
pp. 141-155 ◽  
Author(s):  
Hsu-Wen Chao ◽  
Chen-Jei Hong ◽  
Tzyy-Nan Huang ◽  
Yi-Ling Lin ◽  
Yi-Ping Hsueh
Keyword(s):  
Rna Interference ◽  
Adhesion Molecules ◽  
Hippocampal Neurons ◽  
Time Course ◽  
Pdz Domain ◽  
Spine Density ◽  
Spine Formation ◽  
Protein 4.1 ◽  
Maguk Protein ◽  
Maguk Proteins

Membrane-associated guanylate kinase (MAGUK) proteins interact with several synaptogenesis-triggering adhesion molecules. However, direct evidence for the involvement of MAGUK proteins in synapse formation is lacking. In this study, we investigate the function of calcium/calmodulin-dependent serine protein kinase (CASK), a MAGUK protein, in dendritic spine formation by RNA interference. Knockdown of CASK in cultured hippocampal neurons reduces spine density and shrinks dendritic spines. Our analysis of the time course of RNA interference and CASK overexpression experiments further suggests that CASK stabilizes or maintains spine morphology. Experiments using only the CASK PDZ domain or a mutant lacking the protein 4.1–binding site indicate an involvement of CASK in linking transmembrane adhesion molecules and the actin cytoskeleton. We also find that CASK is SUMOylated. Conjugation of small ubiquitin-like modifier 1 (SUMO1) to CASK reduces the interaction between CASK and protein 4.1. Overexpression of a CASK–SUMO1 fusion construct, which mimicks CASK SUMOylation, impairs spine formation. Our study suggests that CASK contributes to spinogenesis and that this is controlled by SUMOylation.

scholarly journals Rac GEF Dock4 interacts with cortactin to regulate dendritic spine formation

2013 ◽  
Vol 24 (10) ◽  
pp. 1602-1613 ◽  
Author(s):  
Shuhei Ueda ◽  
Manabu Negishi ◽  
Hironori Katoh
Keyword(s):  
Dendritic Spine ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Neuronal Development ◽  
Actin Binding ◽  
Spine Density ◽  
Nucleotide Exchange ◽  
Spine Formation ◽  
Nucleotide Exchange Factor ◽  
Important Interaction

In neuronal development, dendritic spine formation is important for the establishment of excitatory synaptic connectivity and functional neural circuits. Developmental deficiency in spine formation results in multiple neuropsychiatric disorders. Dock4, a guanine nucleotide exchange factor (GEF) for Rac, has been reported as a candidate genetic risk factor for autism, dyslexia, and schizophrenia. We previously showed that Dock4 is expressed in hippocampal neurons. However, the functions of Dock4 in hippocampal neurons and the underlying molecular mechanisms are poorly understood. Here we show that Dock4 is highly concentrated in dendritic spines and implicated in spine formation via interaction with the actin-binding protein cortactin. In cultured neurons, short hairpin RNA (shRNA)–mediated knockdown of Dock4 reduces dendritic spine density, which is rescued by coexpression of shRNA-resistant wild-type Dock4 but not by a GEF-deficient mutant of Dock4 or a truncated mutant lacking the cortactin-binding region. On the other hand, knockdown of cortactin suppresses Dock4-mediated spine formation. Taken together, the results show a novel and functionally important interaction between Dock4 and cortactin for regulating dendritic spine formation via activation of Rac.

scholarly journals Autism-linked mutations of CTTNBP2 reduce social interaction and impair dendritic spine formation via diverse mechanisms

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Pu-Yun Shih ◽  
Bing-Yuan Hsieh ◽  
Ching-Yen Tsai ◽  
Chiu-An Lo ◽  
Brian E. Chen ◽  
...  
Keyword(s):  
Social Interaction ◽  
Dendritic Spine ◽  
Hippocampal Neurons ◽  
Short Form ◽  
Autism Spectrum ◽  
Synaptic Function ◽  
Synaptic Proteins ◽  
Spine Density ◽  
Spine Formation ◽  
Molecular Features

Abstract Abnormal synaptic formation and signaling is one of the key molecular features of autism spectrum disorders (ASD). Cortactin binding protein 2 (CTTNBP2), an ASD-linked gene, is known to regulate the subcellular distribution of synaptic proteins, such as cortactin, thereby controlling dendritic spine formation and maintenance. However, it remains unclear how ASD-linked mutations of CTTNBP2 influence its function. Here, using cultured hippocampal neurons and knockin mouse models, we screen seven ASD-linked mutations in the short form of the Cttnbp2 gene and identify that M120I, R533* and D570Y mutations impair CTTNBP2 protein–protein interactions via divergent mechanisms to reduce dendritic spine density in neurons. R533* mutation impairs CTTNBP2 interaction with cortactin due to lack of the C-terminal proline-rich domain. Through an N–C terminal interaction, M120I mutation at the N-terminal region of CTTNBP2 also negatively influences cortactin interaction. D570Y mutation increases the association of CTTNBP2 with microtubule, resulting in a dendritic localization of CTTNBP2, consequently reducing the distribution of CTTNBP2 in dendritic spines and impairing the synaptic function of CTTNBP2. Finally, we generated heterozygous M120I knockin mice to mimic the genetic variation of patients and found they exhibit reduced social interaction. Our study elucidates that different ASD-linked mutations of CTTNBP2 result in diverse molecular deficits, but all have the similar consequence of synaptic impairment.

scholarly journals Kalirin-7 is a Key Player in the Formation of Excitatory Synapses in Hippocampal Neurons

2010 ◽  
Vol 10 ◽  
pp. 1655-1666 ◽  
Author(s):  
Xin-Ming Ma
Keyword(s):  
Hippocampal Neurons ◽  
Pyramidal Neurons ◽  
Synapse Formation ◽  
Pdz Domain ◽  
Long Term Potentiation ◽  
Binding Motif ◽  
Excitatory Synapses ◽  
Spine Density ◽  
Chronic Cocaine ◽  
And Function

Kalirin-7 (Kal7), a major isoform of Kalirin in the adult rodent hippocampus, is exclusively localized to the postsynaptic side of mature excitatory synapses in hippocampal neurons. Kal7 interacts with multiple PDZ domain—containing proteins through its unique PDZ binding motif. Overexpression of Kal7 increases spine density and spine size, whereas reduction of endogenous Kal7 expression by small hairpin RNA (shRNA) causes a decrease in synapse number and spine density in cultured hippocampal neurons. Hippocampal CA1 pyramidal neurons of Kal7 knockout (Kal7KO) mice show decreased spine density, spine length, synapse number, and postsynaptic density (PSD) size in their apical dendrites; are deficient in long-term potentiation (LTP); and exhibit decreased frequency of spontaneous excitatory postsynaptic current (sEPSC). Kal7 plays a key role in estrogen-mediated spine/synapse formation in hippocampal neurons. Kal7 is also an essential determinant of dendritic spine formation following chronic cocaine treatment. Kal7 plays a key role in excitatory synapse formation and function.

scholarly journals Androgens Modulate NMDA Receptor–Mediated EPSCs in the Zebra Finch Song System

1999 ◽  
Vol 82 (5) ◽  
pp. 2221-2234 ◽  
Author(s):  
Stephanie A. White ◽  
Frederick S. Livingston ◽  
Richard Mooney
Keyword(s):  
Nmda Receptor ◽  
Synaptic Transmission ◽  
Time Course ◽  
Song Learning ◽  
Lateral Part ◽  
Spine Density ◽  
Song System ◽  
Decay Times ◽  
Soma Size

Androgens potently regulate the development of learned vocalizations of songbirds. We sought to determine whether one action of androgens is to functionally modulate the development of synaptic transmission in two brain nuclei, the lateral part of the magnocellular nucleus of the anterior neostriatum (LMAN) and the robust nucleus of the archistriatum (RA), that are critical for song learning and production. We focused on N-methyl-d-aspartate–excitatory postsynaptic currents (NMDA-EPSCs), because NMDA receptor activity in LMAN is crucial to song learning, and because the LMAN synapses onto RA neurons are almost entirely mediated by NMDA receptors. Whole cell recordings from in vitro brain slice preparations revealed that the time course of NMDA-EPSCs was developmentally regulated in RA, as had been shown previously for LMAN. Specifically, in both nuclei, NMDA-EPSCs become faster over development. We found that this developmental transition can be modulated by androgens, because testosterone treatment of young animals caused NMDA-EPSCs in LMAN and RA to become prematurely fast. These androgen-induced effects were limited to fledgling and juvenile periods and were spatially restricted, in that androgens did not accelerate developmental changes in NMDA-EPSCs recorded in a nonsong area, the Wulst. To determine whether androgens had additional effects on LMAN or RA neurons, we examined several other physiological and morphological parameters. In LMAN, testosterone affected α-amino-3-hydroxy-5-methyl-4-isoxazoleproprianate–EPSC (AMPA-EPSC) decay times and the ratio of peak synaptic glutamate to AMPA currents, as well as dendritic length and spine density but did not alter soma size or dendritic complexity. In contrast, testosterone did not affect any of these parameters in RA, which demonstrates that exogenous androgens can have selective actions on different song system neurons. These data are the first evidence for any effect of sex steroids on synaptic transmission within the song system. Our results support the idea that endogenous androgens limit sensitive periods for song learning by functionally altering synaptic transmission in song nuclei.

Glycine regulation of synaptic NMDA receptors in hippocampal neurons

1996 ◽  
Vol 76 (5) ◽  
pp. 3415-3424 ◽  
Author(s):  
K. S. Wilcox ◽  
R. M. Fitzsimonds ◽  
B. Johnson ◽  
M. A. Dichter
Keyword(s):  
Nmda Receptor ◽  
Nmda Receptors ◽  
Hippocampal Neurons ◽  
Time Course ◽  
Hippocampal Slices ◽  
Maximal Effect ◽  
Patch Clamp Technique ◽  
Whole Cell Patch Clamp ◽  
Dissociated Cell Culture ◽  
Cultured Hippocampal Neurons

1. Although glycine has been identified as a required coagonist with glutamate at N-methyl-D-aspartate (NMDA) receptors, the understanding of glycine's role in excitatory synaptic neurotransmission is quite limited. In the present study, we used the whole cell patch-clamp technique to examine the ability of glycine to regulate current flow through synaptic NMDA receptors at excitatory synapses between cultured hippocampal neurons and in acutely isolated hippocampal slices. 2. These studies demonstrate that the glycine modulatory site on the synaptic NMDA receptor is not saturated under baseline conditions and that increased glycine concentrations can markedly increased NMDA-receptor-mediated excitatory postsynaptic currents (EPSCs) in hippocampal neurons in both dissociated cell culture and in slice. Saturation of the maximal effect of glycine takes place at different concentrations for different cells in culture, suggesting the presence of heterogenous NMDA receptor subunit compositions. 3. Bath-applied glycine had no effect on the time course of EPSCs in either brain slice or culture, indicating that desensitization of the NMDA receptor is not prevented by glycine over the time course of an EPSC. 4. When extracellular glycine concentration is high, all miniature EPSCs recorded in the cultured hippocampal neurons contained NMDA components, indicating that segregation of non-NMDA receptors at individual synaptic boutons does not occur.

Gadolinium Reduces AMPA Receptor Desensitization and Deactivation in Hippocampal Neurons

2001 ◽  
Vol 86 (1) ◽  
pp. 173-182 ◽  
Author(s):  
Saobo Lei ◽  
John F. MacDonald
Keyword(s):  
Steady State ◽  
Ampa Receptor ◽  
Hippocampal Neurons ◽  
Time Course ◽  
Single Channel ◽  
Trivalent Cation ◽  
Receptor Desensitization ◽  
Whole Cell ◽  
Low Concentrations ◽  
Cultured Hippocampal Neurons

The actions of the trivalent cation Gd3+ on whole cell AMPA receptor-mediated currents were studied in isolated hippocampal neurons, in nucleated or outside-out patches taken from cultured hippocampal neurons, and on miniature excitatory postsynaptic currents (mEPSCs) recorded in cultured hippocampal neurons. Glutamate, AMPA, or kainate was employed to activate AMPA receptors. Applications of relatively low concentrations of Gd3+ (0.1–10 μM) substantially enhanced steady-state whole cell glutamate and kainate-evoked currents without altering peak currents, suggesting that desensitization was reduced. However, higher concentrations (>30 μM) depressed steady-state currents, indicating an underlying inhibition of channel activity. Lower concentrations of Gd3+also increased the potency of peak glutamate-evoked currents without altering that of steady-state currents. An ultrafast perfusion system and nucleated patches were then used to better resolve peak glutamate-evoked currents. Low concentrations of Gd3+ reduced peak currents, enhanced steady-state currents, and slowed the onset of desensitization, providing further evidence that this cation reduces desensitization. In the presence of cyclothiazide, a compound that blocks desensitization, a low concentration Gd3+ inhibited both peak and steady-state currents, indicating that Gd3+ both reduces desensitization and inhibits these currents. Gd3+ reduced the probability of channel opening at the peak of the currents but did not alter the single channel conductance calculated using nonstationary variance analysis. Recovery from desensitization was enhanced, and glutamate-evoked current activation and deactivation were slowed by Gd3+. The Gd3+-induced reduction in desensitization did not require the presence of the GluR2 subunit as this effect was seen in hippocampal neurons from GluR2 null-mutant mice. Gd3+ reduced the time course of decay of mEPSCs perhaps as a consequence of its slowing of AMPA receptor deactivation although an increase in the frequency of mEPSCs also suggested enhanced presynaptic release of transmitter. These results demonstrate that Gd3+ potently reduces AMPA receptor desensitization and mimics a number of the properties of the positive modulators of AMPA receptor desensitization such as cyclothiazide.

scholarly journals Slitrk2 controls excitatory synapse development via PDZ-mediated protein interactions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kyung Ah Han ◽  
Jinhu Kim ◽  
Hyeonho Kim ◽  
Dongwook Kim ◽  
Dongseok Lim ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Intracellular Signaling ◽  
Hippocampal Neurons ◽  
Pdz Domain ◽  
Protein Tyrosine Phosphatases ◽  
Excitatory Synapse ◽  
Receptor Protein ◽  
Binding Motif ◽  
Synapse Development

AbstractMembers of the Slitrk (Slit- and Trk-like protein) family of synaptic cell-adhesion molecules control excitatory and inhibitory synapse development through isoform-dependent extracellular interactions with leukocyte common antigen-related receptor protein tyrosine phosphatases (LAR-RPTPs). However, how Slitrks participate in activation of intracellular signaling pathways in postsynaptic neurons remains largely unknown. Here we report that, among the six members of the Slitrk family, only Slitrk2 directly interacts with the PDZ domain-containing excitatory scaffolds, PSD-95 and Shank3. The interaction of Slitrk2 with PDZ proteins is mediated by the cytoplasmic COOH-terminal PDZ domain-binding motif (Ile-Ser-Glu-Leu), which is not found in other Slitrks. Mapping analyses further revealed that a single PDZ domain of Shank3 is responsible for binding to Slitrk2. Slitrk2 forms in vivo complexes with membrane-associated guanylate kinase (MAGUK) family proteins in addition to PSD-95 and Shank3. Intriguingly, in addition to its role in synaptic targeting in cultured hippocampal neurons, the PDZ domain-binding motif of Slitrk2 is required for Slitrk2 promotion of excitatory synapse formation, transmission, and spine development in the CA1 hippocampal region. Collectively, our data suggest a new molecular mechanism for conferring isoform-specific regulatory actions of the Slitrk family in orchestrating intracellular signal transduction pathways in postsynaptic neurons.

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