scholarly journals Neuronal cotransport of glycine receptor and the scaffold protein gephyrin

2006 ◽  
Vol 172 (3) ◽  
pp. 441-451 ◽  
Author(s):  
Christoph Maas ◽  
Nadia Tagnaouti ◽  
Sven Loebrich ◽  
Bardo Behrend ◽  
Corinna Lappe-Siefke ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Glycine Receptor ◽  
Scaffold Protein ◽  
Inhibitory Synapses ◽  
Motor Complex ◽  
Neuronal Dendrites ◽  
Dynein Motor ◽  
Cytoskeletal Elements ◽  
Transport Complex ◽  
Activity Dependent

The dynamics of postsynaptic receptor scaffold formation and remodeling at inhibitory synapses remain largely unknown. Gephyrin, which is a multimeric scaffold protein, interacts with cytoskeletal elements and stabilizes glycine receptors (GlyRs) and individual subtypes of γ-aminobutyric acid A receptors at inhibitory postsynaptic sites. We report intracellular mobility of gephyrin transports packets over time. Gephyrin units enter and exit active synapses within several minutes. In addition to previous reports of GlyR–gephyrin interactions at plasma membranes, we show cosedimentation and coimmunoprecipitation of both proteins from vesicular fractions. Moreover, GlyR and gephyrin are cotransported within neuronal dendrites and further coimmunoprecipitate and colocalize with the dynein motor complex. As a result, the blockade of dynein function or dynein–gephyrin interaction, as well as the depolymerization of microtubules, interferes with retrograde gephyrin recruitment. Our data suggest a GlyR–gephyrin–dynein transport complex and support the concept that gephyrin–motor interactions contribute to the dynamic and activity-dependent rearrangement of postsynaptic GlyRs, a process thought to underlie the regulation of synaptic strength.

scholarly journals Differential homeostatic regulation of glycinergic and GABAergic nanocolumns at mixed inhibitory synapses

2020 ◽  
Author(s):  
Xiaojuan Yang ◽  
Hervé Le Corronc ◽  
Pascal Legendre ◽  
Antoine Triller ◽  
Christian G Specht
Keyword(s):  
Spatial Organization ◽  
Super Resolution ◽  
Scaffold Protein ◽  
Synaptic Proteins ◽  
Network Activity ◽  
Inhibitory Synapses ◽  
Homeostatic Regulation ◽  
Synaptic Organization ◽  
Spinal Cord Neurons ◽  
Activity Dependent

AbstractSuper-resolution imaging of synapses has revealed that key synaptic proteins are dynamically organized within sub-synaptic domains (SSDs). At mixed inhibitory synapses in spinal cord neurons, both GlyRs and GABAARs reside at the same post-synaptic density (PSD). To examine how the different inhibitory receptors are organized and regulated, we carried out dual-color direct stochastic optical reconstruction microscopy (dSTORM). We found that endogenous GlyRs and GABAARs as well as their common scaffold protein gephyrin form SSDs that align with pre-synaptic RIM1/2, thus forming trans-synaptic nanocolumns. Strikingly, GlyRs and GABAARs occupy different sub-synaptic spaces, exhibiting only a partial overlap at mixed inhibitory synapses. When network activity was increased by pharmacological treatment using the K+ channel blocker 4-aminopyridine (4-AP), the GABAAR copy numbers of as well as the number of GABAAR SSDs were reduced, while GlyRs remained largely unchanged. This differential regulation is likely the result of changes in gephyrin phosphorylation that preferentially occurred outside of the SSDs. The total gephyrin content was not altered by 4-AP application. The activity-dependent regulation of GABAARs versus GlyRs suggests that different signaling pathways control their respective sub-synaptic organization. Whereas gephyrin serves as a scaffold protein that upholds GlyR numbers at SSDs, it may act as a switch regulating GABAARs via its phosphorylation state. Taken together, our data reinforce the notion that the precise sub-synaptic organization of GlyRs, GABAARs and gephyrin has functional consequences for the homeostatic regulation of mixed inhibitory synapses.HighlightsAlignment of sub-synaptic domains (SSDs) in trans-synaptic nanocolumns at inhibitory synapses Differential spatial organization of SSDs formed by GlyRs and GABAARs at mixed inhibitory synapses Activity-dependent regulation of GABAARs but not GlyRs at mixed inhibitory synapses Gephyrin phosphorylation is compartmentalized in SSDs within the synaptic scaffold

scholarly journals Disease-associated scaffold protein CNK2 modulates PSD size and influences trafficking of new synaptic binding partner TNIK

2019 ◽  
Author(s):  
Hanna L. Zieger ◽  
Stella-Amrei Kunde ◽  
Nils Rademacher ◽  
Bettina Schmerl ◽  
Sarah A. Shoichet
Keyword(s):  
Scaffold Protein ◽  
Subcellular Localisation ◽  
The Novel ◽  
Developmental Defects ◽  
Binding Partner ◽  
Neuronal Dendrites ◽  
Interaction Partners ◽  
Kinase Suppressor Of Ras ◽  
Synaptic Markers

AbstractScaffold proteins are responsible for structural organisation within cells; they form complexes with other proteins to facilitate signalling pathways and catalytic reactions. The scaffold protein connector enhancer of kinase suppressor of Ras 2 (CNK2) is predominantly expressed in neural tissues and was recently implicated in X-linked intellectual disability (ID). We have investigated the role of CNK2 in neurons in order to contribute to our understanding of how CNK2 alterations might cause developmental defects, and we have elucidated a functional role for CNK2 in the molecular processes that govern morphology of the postsynaptic density (PSD). We have also identified novel CNK2 interaction partners and explored their functional interdependency with CNK2. We focussed on the novel interaction partner TRAF2- and NCK-interacting kinase TNIK, which is also associated with ID. Both CNK2 and TNIK are expressed in neuronal dendrites and concentrated in dendritic spines, and staining with synaptic markers indicates a clear postsynaptic localisation. Importantly, our data highlight that CNK2 plays a role in directing TNIK subcellular localisation, and in neurons, CNK2 participates in ensuring that this multifunctional kinase is present at desirable levels at synaptic sites. In summary, our data indicate that CNK2 expression is critical for modulating PSD morphology; moreover, our study highlights a role for CNK2 in directing the localisation of regulatory proteins within the cell. Importantly, we describe a novel link between CNK2 and the regulatory kinase TNIK, and provide evidence supporting the idea that these proteins play complementary roles in the regulation of dendritic spine growth and maintenance.

scholarly journals Redox-assisted regulation of Ca2+ homeostasis in the endoplasmic reticulum by disulfide reductase ERdj5

2016 ◽  
Vol 113 (41) ◽  
pp. E6055-E6063 ◽  
Author(s):  
Ryo Ushioda ◽  
Akitoshi Miyamoto ◽  
Michio Inoue ◽  
Satoshi Watanabe ◽  
Masaki Okumura ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Disulfide Bond ◽  
Plasma Membranes ◽  
Dependent Manner ◽  
Cellular Functions ◽  
Endoplasmic Reticulum Calcium ◽  
Disulfide Reductase ◽  
Intracellular Ca ◽  
Activity Dependent ◽  
Er Calcium

Calcium ion (Ca2+) is an important second messenger that regulates numerous cellular functions. Intracellular Ca2+ concentration ([Ca2+]i) is strictly controlled by Ca2+ channels and pumps on the endoplasmic reticulum (ER) and plasma membranes. The ER calcium pump, sarco/endoplasmic reticulum calcium ATPase (SERCA), imports Ca2+ from the cytosol into the ER in an ATPase activity-dependent manner. The activity of SERCA2b, the ubiquitous isoform of SERCA, is negatively regulated by disulfide bond formation between two luminal cysteines. Here, we show that ERdj5, a mammalian ER disulfide reductase, which we reported to be involved in the ER-associated degradation of misfolded proteins, activates the pump function of SERCA2b by reducing its luminal disulfide bond. Notably, ERdj5 activated SERCA2b at a lower ER luminal [Ca2+] ([Ca2+]ER), whereas a higher [Ca2+]ER induced ERdj5 to form oligomers that were no longer able to interact with the pump, suggesting [Ca2+]ER-dependent regulation. Binding Ig protein, an ER-resident molecular chaperone, exerted a regulatory role in the oligomerization by binding to the J domain of ERdj5. These results identify ERdj5 as one of the master regulators of ER calcium homeostasis and thus shed light on the importance of cross talk among redox, Ca2+, and protein homeostasis in the ER.

Role of Synaptic Inputs in Determining Input Resistance of Developing Brain Stem Motoneurons

2000 ◽  
Vol 84 (5) ◽  
pp. 2317-2329 ◽  
Author(s):  
Pedro A. Núñez-Abades ◽  
John M. Pattillo ◽  
Tracy M. Hodgson ◽  
William E. Cameron
Keyword(s):  
Receptor Antagonist ◽  
Brain Stem ◽  
Glycine Receptor ◽  
Age Groups ◽  
Input Resistance ◽  
Developing Brain ◽  
Inhibitory Synapses ◽  
Combined Application ◽  
Electrode Recording ◽  
Gaba Transmission

The contribution of synaptic input to input resistance was examined in 208 developing genioglossal motoneurons in 3 postnatal age groups (5–7 day, 13–16 day, and 18–24 day) using sharp electrode recording in a slice preparation of the rat brain stem. High magnesium (Mg2+; 6 mM) media generated significant increases (21–38%) in both the input resistance ( R n) and the first time constant (τ0) that were reversible. A large percent of the conductance blocked by high Mg2+ was also sensitive to tetrodotoxin (TTX). Little increase in resistance was attained by adding blockers of specific amino acid (glutamate, glycine, and GABA) transmission over that obtained with the high Mg2+. Comparing across age groups, there was a significantly larger percent change in R n with the addition of high Mg2+ at postnatal days 13 to 15 ( P13–15; 36%) than that found at P5–6 (21%). Spontaneous postsynaptic potentials were sensitive to the combined application of glycine receptor antagonist, strychnine, and the GABAA receptor antagonist, bicuculline. Application of either 10 μM strychnine or bicuculline separately produced a reversible increase in both R n and τ0. Addition of 10 μM bicuculline to a strychnine perfusate failed to further increase either R n or τ0. The strychnine/bicuculline-sensitive component of the total synaptic conductance increased with age so that this form of neurotransmission constituted the majority (>60%) of the observed percent decrease in R n and τ0 in the oldest age group. The proportion of change in τ0 relative to R n following strychnine or high magnesium perfusate varied widely from cell to cell and from age to age without pattern. Based on a model from the literature, this pattern indicates a nonselective distribution of the blocked synaptic conductances over the cell body and dendrites. Taken together, the fast inhibitory synapses (glycine, GABAA) play a greater role in determining cell excitability in developing brain stem motoneurons as postnatal development progresses. These findings suggest that synaptically mediated conductances effect the membrane behavior of developing motoneurons.

scholarly journals Testosterone Signaling through Internalizable Surface Receptors in Androgen Receptor-free Macrophages

1999 ◽  
Vol 10 (10) ◽  
pp. 3113-3123 ◽  
Author(s):  
W. Peter M. Benten ◽  
Michèle Lieberherr ◽  
Olaf Stamm ◽  
Christian Wrehlke ◽  
Zhiyong Guo ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Androgen Receptors ◽  
Surface Receptors ◽  
Toxin Binding ◽  
Agonist Stimulation ◽  
Intracellular Ca ◽  
Cytoskeletal Elements ◽  
G Protein Coupled

Testosterone acts on cells through intracellular transcription-regulating androgen receptors (ARs). Here, we show that mouse IC-21 macrophages lack the classical AR yet exhibit specific nongenomic responses to testosterone. These manifest themselves as testosterone-induced rapid increase in intracellular free [Ca2+], which is due to release of Ca2+from intracellular Ca2+stores. This Ca2+mobilization is also inducible by plasma membrane-impermeable testosterone-BSA. It is not affected by the AR blockers cyproterone and flutamide, whereas it is completely inhibited by the phospholipase C inhibitor U-73122 and pertussis toxin. Binding sites for testosterone are detectable on the surface of intact IC-21 cells, which become selectively internalized independent on caveolae and clathrin-coated vesicles upon agonist stimulation. Internalization is dependent on temperature, ATP, cytoskeletal elements, phospholipase C, and G-proteins. Collectively, our data provide evidence for the existence of G-protein-coupled, agonist-sequestrable receptors for testosterone in plasma membranes, which initiate a transcription-independent signaling pathway of testosterone.

scholarly journals Whacked and Rab35 polarize dynein-motor-complex-dependent seamless tube growth

2012 ◽  
Vol 14 (4) ◽  
pp. 386-393 ◽  
Author(s):  
Jodi Schottenfeld-Roames ◽  
Amin S. Ghabrial
Keyword(s):  
Tube Growth ◽  
Seamless Tube ◽  
Motor Complex ◽  
Dynein Motor

scholarly journals Activity-dependent inhibitory synapse remodeling through gephyrin phosphorylation

2014 ◽  
Vol 112 (1) ◽  
pp. E65-E72 ◽  
Author(s):  
Carmen E. Flores ◽  
Irina Nikonenko ◽  
Pablo Mendez ◽  
Jean-Marc Fritschy ◽  
Shiva K. Tyagarajan ◽  
...  
Keyword(s):  
Activity Patterns ◽  
Phosphorylation Site ◽  
Morphological Plasticity ◽  
Long Term Potentiation ◽  
Inhibitory Synapse ◽  
Inhibitory Synapses ◽  
Synapse Plasticity ◽  
Inhibitory Plasticity ◽  
And Function ◽  
Activity Dependent

Maintaining a proper balance between excitation and inhibition is essential for the functioning of neuronal networks. However, little is known about the mechanisms through which excitatory activity can affect inhibitory synapse plasticity. Here we used tagged gephyrin, one of the main scaffolding proteins of the postsynaptic density at GABAergic synapses, to monitor the activity-dependent adaptation of perisomatic inhibitory synapses over prolonged periods of time in hippocampal slice cultures. We find that learning-related activity patterns known to induce N-methyl-d-aspartate (NMDA) receptor-dependent long-term potentiation and transient optogenetic activation of single neurons induce within hours a robust increase in the formation and size of gephyrin-tagged clusters at inhibitory synapses identified by correlated confocal electron microscopy. This inhibitory morphological plasticity was associated with an increase in spontaneous inhibitory activity but did not require activation of GABAA receptors. Importantly, this activity-dependent inhibitory plasticity was prevented by pharmacological blockade of Ca2+/calmodulin-dependent protein kinase II (CaMKII), it was associated with an increased phosphorylation of gephyrin on a site targeted by CaMKII, and could be prevented or mimicked by gephyrin phospho-mutants for this site. These results reveal a homeostatic mechanism through which activity regulates the dynamics and function of perisomatic inhibitory synapses, and they identify a CaMKII-dependent phosphorylation site on gephyrin as critically important for this process.

scholarly journals A retained intron in the 3′‐ UTR of Calm3 mRNA mediates its Staufen2‐ and activity‐dependent localization to neuronal dendrites

EMBO Reports ◽  
2017 ◽  
Vol 18 (10) ◽  
pp. 1762-1774 ◽  
Author(s):  
Tejaswini Sharangdhar ◽  
Yoichiro Sugimoto ◽  
Jacqueline Heraud‐Farlow ◽  
Sandra M Fernández‐Moya ◽  
Janina Ehses ◽  
...  
Keyword(s):  
Neuronal Dendrites ◽  
Retained Intron ◽  
Activity Dependent

Activity-dependent spatially localized miRNA maturation in neuronal dendrites

Science ◽  
2017 ◽  
Vol 355 (6325) ◽  
pp. 634-637 ◽  
Author(s):  
Sivakumar Sambandan ◽  
Güney Akbalik ◽  
Lisa Kochen ◽  
Jennifer Rinne ◽  
Josefine Kahlstatt ◽  
...  
Keyword(s):  
Neuronal Dendrites ◽  
Activity Dependent
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