scholarly journals Regulation of Neuronal Na,K-ATPase by Extracellular Scaffolding Proteins

2018 ◽  
Vol 19 (8) ◽  
pp. 2214 ◽  
Author(s):  
Thomas Liebmann ◽  
Nicolas Fritz ◽  
Markus Kruusmägi ◽  
Linda Westin ◽  
Kristoffer Bernhem ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Polyclonal Antibodies ◽  
Single Particle Tracking ◽  
Cross Linking ◽  
Scaffolding Proteins ◽  
Sodium Potassium ◽  
Catalytic Subunits ◽  
Energy Expense ◽  
Α3 Subunit ◽  
Na Ions

Neuronal activity leads to an influx of Na+ that needs to be rapidly cleared. The sodium-potassium ATPase (Na,K-ATPase) exports three Na+ ions and imports two K+ ions at the expense of one ATP molecule. Na,K-ATPase turnover accounts for the majority of energy used by the brain. To prevent an energy crisis, the energy expense for Na+ clearance must provide an optimal effect. Here we report that in rat primary hippocampal neurons, the clearance of Na+ ions is more efficient if Na,K-ATPase is laterally mobile in the membrane than if it is clustered. Using fluorescence recovery after photobleaching and single particle tracking analysis, we show that the ubiquitous α1 and the neuron-specific α3 catalytic subunits as well as the supportive β1 subunit of Na,K-ATPase are highly mobile in the plasma membrane. We show that cross-linking of the β1 subunit with polyclonal antibodies or exposure to Modulator of Na,K-ATPase (MONaKA), a secreted protein which binds to the extracellular domain of the β subunit, clusters the α3 subunit in the membrane and restricts its mobility. We demonstrate that clustering, caused by cross-linking or by exposure to MONaKA, reduces the efficiency in restoring intracellular Na+. These results demonstrate that extracellular interactions with Na,K-ATPase regulate the Na+ extrusion efficiency with consequences for neuronal energy balance.

scholarly journals Regulation of GABAergic synapse formation and plasticity by GSK3β-dependent phosphorylation of gephyrin

2010 ◽  
Vol 108 (1) ◽  
pp. 379-384 ◽  
Author(s):  
Shiva K. Tyagarajan ◽  
Himanish Ghosh ◽  
Gonzalo E. Yévenes ◽  
Irina Nikonenko ◽  
Claire Ebeling ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Hippocampal Neurons ◽  
Glycogen Synthase ◽  
Phosphorylation Site ◽  
Scaffolding Protein ◽  
Scaffolding Proteins ◽  
Gabaergic Synapse ◽  
Gabaergic Synapses

Postsynaptic scaffolding proteins ensure efficient neurotransmission by anchoring receptors and signaling molecules in synapse-specific subcellular domains. In turn, posttranslational modifications of scaffolding proteins contribute to synaptic plasticity by remodeling the postsynaptic apparatus. Though these mechanisms are operant in glutamatergic synapses, little is known about regulation of GABAergic synapses, which mediate inhibitory transmission in the CNS. Here, we focused on gephyrin, the main scaffolding protein of GABAergic synapses. We identify a unique phosphorylation site in gephyrin, Ser270, targeted by glycogen synthase kinase 3β (GSK3β) to modulate GABAergic transmission. Abolishing Ser270 phosphorylation increased the density of gephyrin clusters and the frequency of miniature GABAergic postsynaptic currents in cultured hippocampal neurons. Enhanced, phosphorylation-dependent gephyrin clustering was also induced in vitro and in vivo with lithium chloride. Lithium is a GSK3β inhibitor used therapeutically as mood-stabilizing drug, which underscores the relevance of this posttranslational modification for synaptic plasticity. Conversely, we show that gephyrin availability for postsynaptic clustering is limited by Ca2+-dependent gephyrin cleavage by the cysteine protease calpain-1. Together, these findings identify gephyrin as synaptogenic molecule regulating GABAergic synaptic plasticity, likely contributing to the therapeutic action of lithium.

scholarly journals Effect of Handling on ATP Utilization of Cerebral Na,K-ATPase in rats with Trimethyltin-Induced Neurodegeneration.

2021 ◽  
Author(s):  
Barbora Kalocayova ◽  
Denisa Snurikova ◽  
Jana Vlkovicova ◽  
Veronika Navarova Stara ◽  
Dominika Michalikova ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Kinetic Properties ◽  
Potassium Ions ◽  
Catalytic Subunits ◽  
Key Enzyme ◽  
Male Wistar Rats ◽  
Frontal Cerebral Cortex ◽  
Α3 Subunit ◽  
The Brain ◽  
Sodium And Potassium

Abstract Previously it was shown that for reduction of anxiety and stress of experimental animals, preventive handling seems to be one of the most effective methods. The present study was oriented on Na,K-ATPase, a key enzyme for maintaining proper concentrations of intracellular sodium and potassium ions. Malfunction of this enzyme has an essential role in the development of neurodegenerative diseases. It is known that this enzyme requires approximately 50% of the energy available to the brain. Therefore in the present study utilization of the energy source ATP by Na,K-ATPase in the frontal cerebral cortex, using the method of enzyme kinetics was investigated. As a model of neurodegeneration treatment with Trimethyltin (TMT) was applied. Daily handling (10 min/day) of healthy rats and rats suffering neurodegeneration induced by administration of TMT in a dose of (7.5 mg/kg), at postnatal days 60-102 altered the expression of catalytic subunits of Na,K-ATPase as well as kinetic properties of this enzyme in frontal cerebral cortex of adult male Wistar rats. Everyday handling of rats, beside the previously published beneficial effect on spatial memory was accompanied by improwed maintenance of sodium homeeostasis in frontal cortex of brains. The key system responsible for this proces, the Na,K-ATPase was able to utilize better the energy substrate ATP. In rats with TMT-induced neurodegeneration handling promoted the expresion of α2 isoform of the enzyme which is typical for glial cells. In healthy rats the handling was followed by increased expression α3 subunit which is typical for neurons.

scholarly journals Neuronal receptors display cytoskeleton-independent directed motion on the plasma membrane

2018 ◽  
Author(s):  
R. D. Taylor ◽  
M. Heine ◽  
N. J. Emptage ◽  
L. C. Andreae
Keyword(s):  
Plasma Membrane ◽  
Neuronal Activity ◽  
Particle Tracking ◽  
Hippocampal Neurons ◽  
Intracellular Transport ◽  
Transmembrane Proteins ◽  
Single Particle Tracking ◽  
Directed Motion ◽  
Surface Movement ◽  
Transport Vesicles

AbstractDirected transport of transmembrane proteins is generally believed to occur via intracellular transport vesicles. However, using single particle tracking in rat hippocampal neurons with a pH-sensitive quantum dot probe which specifically reports surface movement of receptors, we have identified a subpopulation of neuronal EphB2 receptors that exhibit directed motion between synapses within the plasma membrane itself. This receptor movement occurs independently of the cytoskeleton but is dependent on cholesterol and is regulated by neuronal activity.

BDNF increases synaptic NMDA receptor abundance by enhancing the local translation of Pyk2 in cultured hippocampal neurons

2019 ◽  
Vol 12 (586) ◽  
pp. eaav3577 ◽  
Author(s):  
Pedro Afonso ◽  
Pasqualino De Luca ◽  
Rafael S. Carvalho ◽  
Luísa Cortes ◽  
Paulo Pinheiro ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Hippocampal Neurons ◽  
Protein Tyrosine Kinase ◽  
Cellular Protein ◽  
Single Particle Tracking ◽  
Local Synthesis ◽  
Local Protein Synthesis ◽  
Hnrnp K ◽  
Synaptic Distribution ◽  
Cultured Hippocampal Neurons

The effects of brain-derived neurotrophic factor (BDNF) in long-term synaptic potentiation (LTP) are thought to underlie learning and memory formation and are partly mediated by local protein synthesis. Here, we investigated the mechanisms that mediate BDNF-induced alterations in the synaptic proteome that are coupled to synaptic strengthening. BDNF induced the synaptic accumulation of GluN2B-containing NMDA receptors (NMDARs) and increased the amplitude of NMDAR-mediated miniature excitatory postsynaptic currents (mEPSCs) in cultured rat hippocampal neurons by a mechanism requiring activation of the protein tyrosine kinase Pyk2 and dependent on cellular protein synthesis. Single-particle tracking using quantum dot imaging revealed that the increase in the abundance of synaptic NMDAR currents correlated with their enhanced stability in the synaptic compartment. Furthermore, BDNF increased the local synthesis of Pyk2 at the synapse, and the observed increase in Pyk2 protein abundance along dendrites of cultured hippocampal neurons was mediated by a mechanism dependent on the ribonucleoprotein hnRNP K, which bound to Pyk2 mRNA and dissociated from it upon BDNF application. Knocking down hnRNP K reduced the BDNF-induced synaptic synthesis of Pyk2 protein, whereas its overexpression enhanced it. Together, these findings indicate that hnRNP K mediates the synaptic distribution of Pyk2 synthesis, and hence the synaptic incorporation of GluN2B-containing NMDARs, induced by BDNF, which may affect LTP and synaptic plasticity.

scholarly journals Intracellular Ca 2+ and not the extracellular matrix determines surface dynamics of AMPA-type glutamate receptors on aspiny neurons

2014 ◽  
Vol 369 (1654) ◽  
pp. 20130605 ◽  
Author(s):  
Julia Klueva ◽  
Eckart D. Gundelfinger ◽  
R. Renato Frischknecht ◽  
Martin Heine
Keyword(s):  
Extracellular Matrix ◽  
Glutamate Receptors ◽  
Hippocampal Neurons ◽  
Single Particle Tracking ◽  
Inward Rectification ◽  
Surface Dynamics ◽  
Lateral Mobility ◽  
Spiny Neurons ◽  
Intracellular Ca ◽  
Shaft Synapses

The perisynaptic extracellular matrix (ECM) contributes to the control of the lateral mobility of AMPA-type glutamate receptors (AMPARs) at spine synapses of principal hippocampal neurons. Here, we have studied the effect of the ECM on the lateral mobility of AMPARs at shaft synapses of aspiny interneurons. Single particle tracking experiments revealed that the removal of the hyaluronan-based ECM with hyaluronidase does not affect lateral receptor mobility on the timescale of seconds. Similarly, cross-linking with specific antibodies against the extracellular domain of the GluA1 receptor subunit, which affects lateral receptor mobility on spiny neurons, does not influence receptor mobility on aspiny neurons. AMPARs on aspiny interneurons are characterized by strong inward rectification indicating a significant fraction of Ca 2+ -permeable receptors. Therefore, we tested whether Ca 2+ controls AMPAR mobility in these neurons. Application of the membrane-permeable Ca 2+ chelator BAPTA-AM significantly increased the lateral mobility of GluA1-containing synaptic and extrasynaptic receptors. These data indicate that the perisynaptic ECM affects the lateral mobility differently on spiny and aspiny neurons. Although ECM structures on interneurons appear much more prominent, their influence on AMPAR mobility seems to be negligible at short timescales.

Effect of the Cross-Linking with Calcium Ions on the Structural and Thermo-Mechanical Properties of Alginate Films

2011 ◽  
Vol 1355 ◽  
Author(s):  
Turner K. Vidal Urquiza ◽  
O. Perales Pérez ◽  
M. Gálvez Saldaña
Keyword(s):  
Calcium Ions ◽  
Calcium Alginate ◽  
Immersion Time ◽  
Nitrogen Atmosphere ◽  
Cross Linking ◽  
Molecular Response ◽  
Vibration Modes ◽  
Ca Ions ◽  
Na Ions ◽  
Response To Temperature

ABSTRACTThe present research discusses the thermal and structural properties of calcium alginate films synthesized by cross linking precursor sodium alginate films with Ca2+ ions. Raman and FTIR spectroscopy analyses evinced the interchange of Na ions with Ca ions. Both techniques revealed a shift of the COO- vibration modes; the symmetrical COO- peak of calcium alginate exhibited a shift towards higher wavenumber (∼14 cm−1) from 1415 cm−1 to 1429 cm−1 in the Raman spectra. TGA and TMA analyses performed under a nitrogen atmosphere revealed that increasing the Ca-molarity and immersion time resulted in an increase in the glass transition temperature (Tg) and the strain deformation of the Ca-alginate film. The increase in Tg can be attributed to the Ca-cross-linking that could restrict the molecular response to temperature change whereas the increased strain could be due to the enhanced entrapment of water between the molecular chains of the polymer.

scholarly journals Hampered diffusion of neuropilin-1 and lipids in the plasma membrane of hippocampal neurons as studied by single particle tracking and optical tweezers.

1999 ◽  
Vol 39 (supplement) ◽  
pp. S95
Author(s):  
C. Nakada ◽  
T. Hirata ◽  
T. Kawasaki ◽  
K. Yamaguchi ◽  
H. Fujisawa ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Optical Tweezers ◽  
Particle Tracking ◽  
Single Particle ◽  
Hippocampal Neurons ◽  
Single Particle Tracking ◽  
Neuropilin 1

scholarly journals Downregulation of Filamin a Expression in the Aorta Is Correlated With Aortic Dissection

2021 ◽  
Vol 8 ◽  
Author(s):  
Yue Chen ◽  
Xiang Wei ◽  
Zihao Zhang ◽  
Yi He ◽  
Bo Huo ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
Gene Expression Omnibus ◽  
Cross Linking ◽  
Mrna Levels ◽  
Scaffolding Proteins ◽  
Filamin A ◽  
Cellular Functions ◽  
Expression Levels ◽  
Protein Levels ◽  
Geo Database

Filamins (FLNs) are actin cross-linking proteins, and as scaffolding proteins, FLNs are closely associated with the stabilization of the cytoskeleton. Nevertheless, the biological importance of FLNs in aortic dissection (AD) has not been well-elucidated. In this study, we first reanalyzed datasets downloaded from the Gene Expression Omnibus (GEO) database, and we found that in addition to the extracellular matrix, the actin cytoskeleton is a key structure associated with AD. Given that FLNs are involved in remodeling the cytoskeleton to affect cellular functions, we measured their expression levels in the aortas of patients with Stanford type A AD (TAAD). Our results showed that the mRNA and protein levels of FLNA were consistently decreased in dissected aortas of both humans and mice, while the FLNB protein level was upregulated despite decreased FLNB mRNA levels, and comparable expression levels of FLNC were observed between groups. Furthermore, the immunohistochemistry results demonstrated that FLNA was highly expressed in smooth muscle cells (SMCs) of aorta in non-AD samples, and downregulated in the medial layer of the dissected aortas of humans and mice. Moreover, we revealed that FOS and JUN, forming a dimeric transcription factor called AP-1 (activating protein-1), were positively correlated with the expression of FLNA in aorta. Either overexpression of FOS or JUN alone, or overexpression of FOS and JUN together, facilitated the expression of FLNA in primary cultured human aortic SMCs. In the present study, we not only detected the expression pattern of FLNs in aortas of humans and mice with or without AD, but we also found that the expression of FLNA in the AD samples was significantly reduced and that AP-1 might regulate the expression of FLNA. Our findings will contribute to the elucidation of the pathological mechanisms of AD and provide potential therapeutic targets for AD.

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