scholarly journals Transport of PIP3 by GAKIN, a kinesin-3 family protein, regulates neuronal cell polarity

2006 ◽  
Vol 174 (3) ◽  
pp. 425-436 ◽  
Author(s):  
Kaori Horiguchi ◽  
Toshihiko Hanada ◽  
Yasuhisa Fukui ◽  
Athar H. Chishti
Keyword(s):  
Hippocampal Neurons ◽  
Neuronal Cell ◽  
Neuronal Polarity ◽  
Transport Activity ◽  
Phosphatidylinositol 3 Kinase ◽  
Interacting Protein ◽  
Family Protein ◽  
Axon Specification ◽  
Cultured Hippocampal Neurons

Phosphatidylinositol-(3,4,5)-trisphosphate (PIP3), a product of phosphatidylinositol 3-kinase, is an important second messenger implicated in signal transduction and membrane transport. In hippocampal neurons, the accumulation of PIP3 at the tip of neurite initiates the axon specification and neuronal polarity formation. We show that guanylate kinase–associated kinesin (GAKIN), a kinesin-like motor protein, directly interacts with a PIP3-interacting protein, PIP3BP, and mediates the transport of PIP3-containing vesicles. Recombinant GAKIN and PIP3BP form a complex on synthetic liposomes containing PIP3 and support the motility of the liposomes along microtubules in vitro. In PC12 cells and cultured hippocampal neurons, transport activity of GAKIN contributes to the accumulation of PIP3 at the tip of neurites. In hippocampal neurons, altered accumulation of PIP3 by overexpression of GAKIN constructs led to the loss of the axonally differentiated neurites. Together, these results suggest that, in neurons, the GAKIN–PIP3BP complex transports PIP3 to the neurite ends and regulates neuronal polarity formation.

Neurotrophic Properties of Silexan, an Essential Oil from the Flowers of Lavender-Preclinical Evidence for Antidepressant-Like Properties

2020 ◽  
Vol 54 (01) ◽  
pp. 37-46
Author(s):  
Kristina Friedland ◽  
Giacomo Silani ◽  
Anita Schuwald ◽  
Carola Stockburger ◽  
Egon Koch ◽  
...  
Keyword(s):  
Essential Oil ◽  
Hippocampal Neurons ◽  
Day Treatment ◽  
Neuronal Cell ◽  
Antidepressant Activity ◽  
In Vivo Models ◽  
Antidepressant Effects ◽  
Primary Hippocampal Neurons

Abstract Background Silexan, a special essential oil from flowering tops of lavandula angustifolia, is used to treat subsyndromal anxiety disorders. In a recent clinical trial, Silexan also showed antidepressant effects in patients suffering from mixed anxiety-depression (ICD-10 F41.2). Since preclinical data explaining antidepressant properties of Silexan are missing, we decided to investigate if Silexan also shows antidepressant-like effects in vitro as well as in vivo models. Methods We used the forced swimming test (FST) in rats as a simple behavioral test indicative of antidepressant activity in vivo. As environmental events and other risk factors contribute to depression through converging molecular and cellular mechanisms that disrupt neuronal function and morphology—resulting in dysfunction of the circuitry that is essential for mood regulation and cognitive function—we investigated the neurotrophic properties of Silexan in neuronal cell lines and primary hippocampal neurons. Results The antidepressant activity of Silexan (30 mg/kg BW) in the FST was comparable to the tricyclic antidepressant imipramine (20 mg/kg BW) after 9-day treatment. Silexan triggered neurite outgrowth and synaptogenesis in 2 different neuronal cell models and led to a significant increase in synaptogenesis in primary hippocampal neurons. Silexan led to a significant phosphorylation of protein kinase A and subsequent CREB phosphorylation. Conclusion Taken together, Silexan demonstrates antidepressant-like effects in cellular as well as animal models for antidepressant activity. Therefore, our data provides preclinical evidence for the clinical antidepressant effects of Silexan in patients with mixed depression and anxiety.

scholarly journals Serum- and Glucocorticoid-Inducible Kinase 1 (SGK1) Increases Neurite Formation through Microtubule Depolymerization by SGK1 and by SGK1 Phosphorylation oftau

2006 ◽  
Vol 26 (22) ◽  
pp. 8357-8370 ◽  
Author(s):  
Ying C. Yang ◽  
Cheng H. Lin ◽  
Eminy H. Y. Lee
Keyword(s):  
Hippocampal Neurons ◽  
Kinase Assay ◽  
Phosphorylated Tau ◽  
Microtubule Depolymerization ◽  
Independent Manner ◽  
Cell Functions ◽  
Neurite Formation ◽  
Cultured Hippocampal Neurons

ABSTRACT Serum- and glucocorticoid-inducible kinase 1 (SGK1) is a member of the Ser/Thr protein kinase family that regulates a variety of cell functions. Recently, SGK1 was shown to increase dendritic growth but the mechanism underlying the increase is unknown. Here we demonstrated that SGK1 increased the neurite formation of cultured hippocampal neurons through microtubule (MT) depolymerization via two distinct mechanisms. First, SGK1 directly depolymerized MTs. In vitro MT depolymerization experiments revealed that SGK1, especially N-truncated SGK1, directly disassembled self-polymerized MTs and taxol-stabilized MTs in a dose-dependent and ATP-independent manner. The transfection of sgk1 to HeLa cells also inhibited MT assembly in vivo. Second, SGK1 indirectly depolymerized MTs through the phosphorylation of tau at Ser214. An in vitro kinase assay revealed that active SGK1 phosphorylated tau Ser214 specifically. In vivo transfection of sgk1 also phosphorylated tau Ser214 in HEK293T cells and hippocampal neurons. Further, sgk1 transfection significantly increased the number of primary neurites and shortened the length of the total process in cultured hippocampal neurons. These effects were antagonized by the cotransfection of the tauS214A mutant plasmid. Dexamethasone, a synthetic glucocorticoid, mimics the effect of sgk1 overexpression. Together, these results suggest that SGK1 enhances neurite formation through MT depolymerization by a direct action of SGK1 and by the SGK1 phosphorylation of tau.

scholarly journals Differential neurite outgrowth is required for axon specification by cultured hippocampal neurons

2012 ◽  
Vol 123 (6) ◽  
pp. 904-910 ◽  
Author(s):  
Hideaki Yamamoto ◽  
Takanori Demura ◽  
Mayu Morita ◽  
Gary A. Banker ◽  
Takashi Tanii ◽  
...  
Keyword(s):  
Neurite Outgrowth ◽  
Hippocampal Neurons ◽  
Axon Specification ◽  
Cultured Hippocampal Neurons

scholarly journals Neuronal Cells Confinement by Micropatterned Cluster-Assembled Dots with Mechanotransductive Nanotopography

2018 ◽  
Author(s):  
Carsten Schulte ◽  
Jacopo Lamanna ◽  
Andrea Stefano Moro ◽  
Claudio Piazzoni ◽  
Francesca Borghi ◽  
...  
Keyword(s):  
Neural Networks ◽  
Hippocampal Neurons ◽  
Neural Circuit ◽  
Neuronal Cells ◽  
Neuronal Cell ◽  
Deep Understanding ◽  
Glass Substrates ◽  
Wide Range ◽  
Controlled Structure

ABSTRACTThe in vitro fabrication of neural networks able to simulate brain circuits and to maintain their native connectivity is of strategic importance to gain a deep understanding of neural circuit physiology and brain natural computational algorithm(s). This would also enable a wide-range of applications including the development of efficient brain-on-chip devices or brain-computer interfaces. Chemical and mechanotransductive cues cooperate to promote proper development and functioning of neural networks. Since the 80’s, controlled growth of mammalian neuronal cells on micrometric patterned chemical cues with the development of synaptic connections and electrical activity has been reported, however the role of mechanotransductive signaling on the growth/organization of neural networks has not been investigated so far. Here we report the fabrication and characterization of patterned substrates for neuronal culture with a controlled structure both at the nano- and microscale suitable for the selective adhesion of neuronal cells. Nanostructured micrometric dots were patterned on passivated cell-repellent glass substrates by supersonic cluster beam deposition of zirconia nanoparticles through stencil masks. Cluster-assembled nanostructured zirconia surfaces are characterized by nanotopographical features that can direct the maturation of neural networks by mechanotransductive signaling. Our approach produces a controlled microscale pattern of adhesive areas with predetermined nanoscale morphology. We have validated these micropatterned substrates using a neuronal cell line (PC12 cells) and cultured hippocampal neurons. While cells have been uniformly plated on the substrates, they adhered only on the nanostructured zirconia regions, remaining effectively confined inside the nanostructured dots on which they were found to grow, move and differentiate.

Synaptic and Extrasynaptic NMDA Receptor NR2 Subunits in Cultured Hippocampal Neurons

2006 ◽  
Vol 95 (3) ◽  
pp. 1727-1734 ◽  
Author(s):  
Christopher G. Thomas ◽  
Ashleigh J. Miller ◽  
Gary L. Westbrook
Keyword(s):  
Nmda Receptors ◽  
Hippocampal Neurons ◽  
Synapse Formation ◽  
Whole Cell ◽  
Extrasynaptic Receptors ◽  
C Terminus ◽  
Specific Antagonist ◽  
Nr2 Subunits ◽  
Cultured Hippocampal Neurons

Early in development, neurons only express NR1/NR2B-containing N-methyl-d-aspartate (NMDA) receptors. Later, NR2A subunits are upregulated during a period of rapid synapse formation. This pattern is often interpreted to indicate that NR2A-containing receptors are synaptic and that NR2B-containing receptors are extrasynaptic. We re-examined this issue using whole cell recordings in cultured hippocampal neurons. As expected, the inhibition of whole cell currents by the NR2B-specific antagonist, ifenprodil, progressively decreased from 69.5 ± 2.4% [6 days in vitro (DIV)] to 54.9 ± 2.6% (8 DIV), before reaching a plateau in the second week (42.5 ± 2%, 12–19 DIV). In NR2A−/− neurons, which express only NR1/NR2B-containing NMDA receptors, autaptic excitatory postsynaptic currents (EPSCs; ≥12 DIV) were more sensitive to ifenprodil and decayed more slowly than EPSCs in wild-type neurons. Thus NR2B-containing receptors were not excluded from synapses. We blocked synaptic NMDA receptors with MK-801 during evoked transmitter release, thus allowing us to isolate extrasynaptic receptors. Ifenprodil inhibition of this extrasynaptic population was highly variable in different neurons. Furthermore, extrasynaptic receptors in autaptic cultures were only partially blocked by ifenprodil, indicating that NR2A-containing receptors are not exclusively confined to the synapse. Extrasynaptic NR2A-containing receptors were also detected in NR2A−/− neurons transfected with full-length NR2A. Truncation of the NR2A C terminus did not eliminate synaptic expression of NR2A-containing receptors. Our results indicate that NR2A- and NR2B-containing receptors can be located in either synaptic or extrasynaptic compartments.

scholarly journals Ps in the (Channel) Pod Are Not Alike …

2007 ◽  
Vol 7 (5) ◽  
pp. 136-137
Author(s):  
Yoav Noam ◽  
Tallie Z. Baram
Keyword(s):  
Neuronal Activity ◽  
Hippocampal Neurons ◽  
Neuronal Excitability ◽  
Phosphorylation Sites ◽  
Voltage Dependent ◽  
Activity Dependent ◽  
Stimulation Of ◽  
Cultured Hippocampal Neurons

Bidirectional Activity-Dependent Regulation of Neuronal Ion Channel Phosphorylation. Misonou H, Menegola M, Mohapatra DP, Guy LK, Park KS, Trimmer JS. J Neurosci 2006;26(52):13505–13514. Activity-dependent dephosphorylation of neuronal Kv2.1 channels yields hyperpolarizing shifts in their voltage-dependent activation and homoeostatic suppression of neuronal excitability. We recently identified 16 phosphorylation sites that modulate Kv2.1 function. Here, we show that in mammalian neurons, compared with other regulated sites, such as serine (S)563, phosphorylation at S603 is supersensitive to calcineurin-mediated dephosphorylation in response to kainate-induced seizures in vivo, and brief glutamate stimulation of cultured hippocampal neurons. In vitro calcineurin digestion shows that supersensitivity of S603 dephosphorylation is an inherent property of Kv2.1. Conversely, suppression of neuronal activity by anesthetic in vivo causes hyperphosphorylation at S603 but not S563. Distinct regulation of individual phosphorylation sites allows for graded and bidirectional homeostatic regulation of Kv2.1 function. S603 phosphorylation represents a sensitive bidirectional biosensor of neuronal activity.

Contact guidance of CNS neurites on grooved quartz: influence of groove dimensions, neuronal age and cell type

1997 ◽  
Vol 110 (23) ◽  
pp. 2905-2913 ◽  
Author(s):  
A. Rajnicek ◽  
S. Britland ◽  
C. McCaig
Keyword(s):  
Hippocampal Neurons ◽  
Growth Cones ◽  
Companion Paper ◽  
Contact Guidance ◽  
Neuronal Polarity ◽  
Cell Type ◽  
Spinal Cord Neurons ◽  
In Vitro System ◽  
Guidance Information

We used an in vitro system that eliminates competing guidance cues found in embryos to determine whether substratum topography alone provides important neurite guidance information. Dissociated embryonic Xenopus spinal cord neurons and rat hippocampal neurons were grown on quartz etched with a series of parallel grooves. Xenopus neurites grew parallel to grooves as shallow as 14 nm and as narrow as 1 microm. Hippocampal neurites grew parallel to deep, wide grooves but perpendicular to shallow, narrow ones. Grooved substrata determined the sites at which neurites emerged from somas: Xenopus neurites sprouted from regions parallel to grooves but presumptive axons on rat hippocampal neurons emerged perpendicular to grooves and presumptive dendrites emerged parallel to them. Neurites grew faster in the favored direction of orientation and turned through large angles to align on grooves. The frequency of perpendicular alignment of hippocampal neurites depended on the age of the embryos from which neurons were isolated, suggesting that contact guidance is regulated in development. Collectively, the data indicate that substratum topography is a potent morphogenetic factor for developing CNS neurons and suggest that in addition to a role in pathfinding the geometry of the embryo assists in establishing neuronal polarity. In the companion paper (A. M. Rajnicek and C. D. McCaig (1997) J. Cell Sci. 110, 2915–2924) we explore the cellular mechanism for contact guidance of growth cones.

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