scholarly journals Gamma-protocadherin localization at the synapse corresponds to parameters of synaptic maturation

2019 ◽  
Author(s):  
Nicole LaMassa ◽  
Hanna Sverdlov ◽  
Aliya Mambetalieva ◽  
Stacy Shapiro ◽  
Michael Bucaro ◽  
...  
Keyword(s):  
Neural Development ◽  
Cortical Neurons ◽  
Hippocampal Neurons ◽  
Large Family ◽  
Large Gene ◽  
Intracellular Compartments ◽  
Synaptic Maturation ◽  
Knockout Animals ◽  
Mushroom Spines

AbstractClustered protocadherins (Pcdhs) are a large family of ~60 cadherin-like proteins (divided into the subclasses α, β, and γ) that compose a surface “barcode” in individual neurons. The code is generated through combinatorial expression via epigenetic regulation at a large gene cluster that encodes the molecules. During early neural development, Pcdhs were shown to mediate dendrite self-avoidance in some neuronal types through a still uncharacterized anti-adhesive mechanism. Pcdhs were also shown to be important for dendritic complexity in cortical neurons likely through a pro-adhesive mechanism. Pcdhs have also been postulated to participate in synaptogenesis and the specificity of connectivity. Some synaptic defects were noted in knockout animals, including synaptic number and physiology, but the role of these molecules in synaptic development is not understood. The effects of Pcdh knockout on dendritic patterning may present a confound to studying synaptogenesis. We have shown previously in vivo and in cultures that Pcdh-γs are highly enriched in intracellular compartments located in dendrites and spines with localization at only a few synaptic clefts. To gain insight into how Pcdh-γs might affect synapses, we compared synapses that harbored endogenous Pcdh-γs versus those that did not for parameters of synaptic maturation including pre- and postsynaptic size, postsynaptic perforations, and spine morphology by light microscopy in cultured hippocampal neurons and by serial section immuno-electron microscopy in hippocampal CA1. In mature neurons, synapses immunopositive for Pcdh-γs were found to be larger in diameter with more frequent perforations. Analysis of spines in cultured neurons revealed that mushroom spines were more frequently immunopositive for Pcdh-γs at their tips than thin spines. Taken together, these results suggest that Pcdh-γ function at the synapse may be related to promotion of synaptic maturation and stabilization.

Defective Activation of Phospholipase Cγ2 by Collagen in Platelets Lacking the Semaphorin Family Member, Sema4D.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 417-417 ◽  
Author(s):  
Li Zhu ◽  
Hong Jiang ◽  
Atsushi Kumanogoh ◽  
Hitoshi Kikutani ◽  
Lawrence F. Brass
Keyword(s):  
Platelet Aggregation ◽  
Family Member ◽  
Neural Development ◽  
Tyrosine Phosphatase ◽  
Large Family ◽  
Arterial Injury ◽  
Human Platelets ◽  
Glycoprotein Vi

Abstract Semaphorins are a large family of cell surface molecules best known for their ability to mediate communication between cells during neural development. We have recently shown that human platelets express the semaphorin family member, sema4D, and both of its known receptors, CD72 and plexin-B1 (Zhu, et al, PNAS, 2007). We have also shown that sema4D(−/−) mice have an impaired response to arterial injury in vivo and a selective defect in collagen- and convulxin-induced platelet aggregation in vitro. In the present studies we have sought the molecular basis for these defects, focusing on events downstream of glycoprotein VI (GPVI), which serves as a receptor for both collagen and convulxin. In normal platelets, GPVI signaling leads to the phosphorylation and activation of phospholipase Cγ2 (PLCγ2) through the formation of a signaling complex that includes SLP-76 and LAT. This complex is activated when GPVI-associated FcRγ is phosphorylated, allowing the tyrosine kinase, Syk, to bind. PLCγ2 activation results in phosphoinositide hydrolysis, an IP3-mediated increase in cytosolic Ca++, and activation of additional kinases, such as Akt. In theory, the absence of sema4D could affect any of these steps and by doing so impair collagen-induced platelet aggregation. Working backwards through the GPVI pathway, our results showed that compared to platelets from matched WT mice, sema4D(−/−) platelets have 1) a rightward-shift in the dose/response curve for collagen-induced Akt phosphorylation, 2) a 37% smaller increase in cytosolic Ca++, and 3) a 43% smaller increase in PLCγ2 phosphorylation. However, we found no defect in collagen-induced FcRγ phosphorylation, which is the earliest event in GPVI signaling. The defect in PLCγ2 phosphorylation was not limited to mouse platelets, but was also observed when human platelets were stimulated with collagen in the presence of an antibody directed towards the sema4D extracellular domain. Taken together, these results show that sema4D is needed for optimal activation of PLCγ2 by collagen downstream of the GPVI/FcRγ complex. Sema4D is believed to act in part through contact-dependent binding of sema4D to its receptors, CD72 and plexin-B1. Since these studies were performed under conditions in which platelet:platelet contacts can occur, the observed defect in collagen and convulxin responses could be due to impaired signaling by either of these receptors or, in theory, by retrograde signaling via sema4D. One candidate mechanism involves a regulatory complex between CD72 and the tyrosine phosphatase, SHP-1, which we have shown to occur in resting human platelets and to be lost when platelets are activated by agonists or stimulated by soluble sema4D. In theory, sema4D-dependent loss of the CD72/SHP-1 complex allows SHP-1 to relax into an inactive conformation, promoting protein tyrosine phosphorylation, which would not occur when sema4D is absent or blocked.

scholarly journals Basic FGF, NGF, and IGFs Protect Hippocampal and Cortical Neurons against Iron-Induced Degeneration

1993 ◽  
Vol 13 (3) ◽  
pp. 378-388 ◽  
Author(s):  
Ying Zhang ◽  
Tohru Tatsuno ◽  
John M. Carney ◽  
Mark P. Mattson
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Cortical Neurons ◽  
Hippocampal Neurons ◽  
Neuronal Degeneration ◽  
Cell Damage ◽  
Oxygen Radical ◽  
Neuroprotective Effects ◽  
In Vivo Models

Iron is believed to contribute to the process of cell damage and death resulting from ischemic and traumatic insults by catalyzing the oxidation of protein and lipids. Exposure of cultured rat hippocampal neurons to iron (FeSO4) caused a dose-dependent reduction in neuronal survival, which was potentiated by ascorbate. Damage to neurons was associated with a significant level of oxygen radical in the culture medium. The iron chelator desferal prevented both the neuronal degeneration caused by FeSO4 and the production of oxygen radical, demonstrating that ionic iron was responsible for the cell damage. Iron neurotoxicity was associated with an elevation of [Ca2+]i and was attenuated by NMDA receptor antagonists. Since recent findings demonstrated neuroprotective effects of growth factors in cell culture and in vivo models of ischemia, we examined the effects of growth factors on iron-induced damage. Basic fibroblast growth factor (bFGF), nerve growth factor (NGF), and insulinlike growth factors (IGF-I and IGF-II) each protected neurons against iron-induced damage. Both rat hippocampal and human cortical neurons were protected by these growth factors. Taken together, the data suggest that the neuroprotective effects of growth factors against excitotoxic/ischemic insults may result, in part, from a prevention or attenuation of oxidative damage.

scholarly journals c-Jun NH2-terminal Kinase (JNK)-interacting Protein-3 (JIP3) Regulates Neuronal Axon Elongation in a Kinesin- and JNK-dependent Manner

2013 ◽  
Vol 288 (20) ◽  
pp. 14531-14543 ◽  
Author(s):  
Tao Sun ◽  
Nuo Yu ◽  
Lu-Kai Zhai ◽  
Na Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Neuronal Development ◽  
Dependent Manner ◽  
Loss Of Function ◽  
Anterograde Transport ◽  
Interacting Protein ◽  
Axon Elongation

The development of neuronal polarity is essential for the establishment of the accurate patterning of neuronal circuits in the brain. However, little is known about the underlying molecular mechanisms that control rapid axon elongation during neuronal development. Here, we report that c-Jun NH2-terminal kinase (JNK)-interacting protein-3 (JIP3) is highly expressed at axon tips during the critical period for axon development. Using gain- and loss-of-function approaches, immunofluorescence analysis, and in utero electroporation, we find that JIP3 can enhance axon elongation in primary hippocampal neurons and cortical neurons in vivo. We further demonstrate that JIP3 promotes axon elongation in a kinesin- and JNK-dependent manner using several deletion mutants of JIP3. Next, we demonstrate that the successful transportation of JIP3 to axon tips by kinesin is a prerequisite for enhancing JNK phosphorylation in this area and therefore promotes axon elongation, constituting a novel mechanism for coupling JIP3 anterograde transport with JNK signaling at the distal axons and axon elongation. Finally, our immunofluorescence data suggest that the activation of JNK at axon tips facilitates axon elongation by modulating cofilin activity and actin filament dynamics. These findings may have important implications for our understanding of neuronal axon elongation during development.

scholarly journals Mfn2 Ablation in the Adult Mouse Hippocampus and Cortex Causes Neuronal Death

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 116 ◽  
Author(s):  
Song Han ◽  
Priya Nandy ◽  
Quillan Austria ◽  
Sandra L. Siedlak ◽  
Sandy Torres ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cortical Neurons ◽  
Hippocampal Neurons ◽  
Adult Mouse ◽  
Nuclear Antigen ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Mitochondrial Fragmentation ◽  
Knock Out ◽  
Aberrant Cell

It is believed that mitochondrial fragmentation cause mitochondrial dysfunction and neuronal deficits in Alzheimer’s disease. We recently reported that constitutive knockout of the mitochondria fusion protein mitofusin2 (Mfn2) in the mouse brain causes mitochondrial fragmentation and neurodegeneration in the hippocampus and cortex. Here, we utilize an inducible mouse model to knock out Mfn2 (Mfn2 iKO) in adult mouse hippocampal and cortical neurons to avoid complications due to developmental changes. Electron microscopy shows the mitochondria become swollen with disorganized and degenerated cristae, accompanied by increased oxidative damage 8 weeks after induction, yet the neurons appear normal at the light level. At later timepoints, increased astrocyte and microglia activation appear and nuclei become shrunken and pyknotic. Apoptosis (Terminal deoxynucleotidyl transferase dUTP nick end labeling, TUNEL) begins to occur at 9 weeks, and by 12 weeks, most hippocampal neurons are degenerated, confirmed by loss of NeuN. Prior to the loss of NeuN, aberrant cell-cycle events as marked by proliferating cell nuclear antigen (PCNA) and pHistone3 were evident in some Mfn2 iKO neurons but do not colocalize with TUNEL signals. Thus, this study demonstrated that Mfn2 ablation and mitochondrial fragmentation in adult neurons cause neurodegeneration through oxidative stress and neuroinflammation in vivo via both apoptosis and aberrant cell-cycle-event-dependent cell death pathways.

scholarly journals Depletion of Intracellular Zinc from Neurons by Use of an Extracellular Chelator In Vivo and In Vitro

2002 ◽  
Vol 50 (12) ◽  
pp. 1659-1662 ◽  
Author(s):  
Christopher J. Frederickson ◽  
Sang W. Suh ◽  
Jae-Young Koh ◽  
Yoo K. Cha ◽  
Richard B. Thompson ◽  
...  
Keyword(s):  
General Result ◽  
Cortical Neurons ◽  
Zinc Ion ◽  
Purkinje Neurons ◽  
Intracellular Zinc ◽  
Ion Efflux ◽  
Intracellular Compartments ◽  
The Brain

The membrane-impermeable chelator CaEDTA was introduced extracellularly among neurons in vivo and in vitro for the purpose of chelating extracellular Zn2+. Unexpectedly, this treatment caused histochemically reactive Zn2+ in intracellular compartments to drop rapidly. The same general result was seen with intravesicular Zn2+, which fell after CaEDTA infusion into the lateral ventricle of the brain, with perikaryal Zn2+ in Purkinje neurons (in vivo) and with cortical neurons (in vitro). These findings suggest either that the volume of zinc ion efflux and reuptake is higher than previously suspected or that EDTA can enter cells and vesicles. Caution is therefore warranted in attempting to manipulate extracellular or intracellular Zn2+ selectively.

scholarly journals Chronic Ca2+ imaging of cortical neurons with long-term expression of GCaMP-X

2022 ◽  
Author(s):  
Jinli Geng ◽  
Wenxiang Li ◽  
Yingjun Tang ◽  
Yunming Gao ◽  
Yitong Lu ◽  
...  
Keyword(s):  
Neural Development ◽  
Cortical Neurons ◽  
Intracellular Signaling ◽  
Sensory Response ◽  
Imaging Data ◽  
Membrane Excitability ◽  
Sensory Evoked

Dynamic Ca2+ signals reflect acute changes in membrane excitability (e.g. sensory response), and also mediate intracellular signaling cascades normally of longer time scales (e.g., Ca2+- dependent neuritogenesis). In both cases, chronic Ca2+ imaging has been often desired, but largely hindered by unexpected cytotoxicity intrinsic to GCaMP, a popular series of genetically-encoded Ca2+ indicators. Here, we demonstrate that the recently developed GCaMP-X outperforms GCaMP in long-term probe expression and/or chronic Ca2+ imaging. GCaMP-X shows much improved compatibility with neurons and thus more reliable than GCaMP as demonstrated in vivo by acute Ca2+ responses to whisker deflection or spontaneous Ca2+ fluctuations over an extended time frame. Chronic Ca2+ imaging data (≥1 month) are acquired from the same set of cultured cortical neurons, unveiling that spontaneous/local Ca2+ activities would progressively develop into autonomous/global Ca2+ oscillations. Besides the morphological indices of neurite length or soma size, the major metrics of oscillatory Ca2+, including rate, amplitude, synchrony among different neurons or organelles have also been examined along with the developmental stages. Both neuritogenesis and Ca2+ signals are dysregulated by GCaMP in virus-infected or transgenic neurons, in direct contrast to GCaMP-X without any noticeable side-effect. Such in vitro data altogether consolidate the unique importance of oscillatory Ca2+ to activity-dependent neuritogenesis, as one major factor responsible for the distinctions between GCaMP vs GCaMP-X in vivo. For the first time with GCaMP-X of long-term expression in neurons, spontaneous and sensory-evoked Ca2+ activities are imaged and evaluated both in vitro and in vivo, providing new opportunities to monitor neural development or other chronic processes concurrently with Ca2+ dynamics.

scholarly journals Phosphorylation of CRMP2 by Cdk5 Regulates Dendritic Spine Development of Cortical Neuron in the Mouse Hippocampus

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaohua Jin ◽  
Kodai Sasamoto ◽  
Jun Nagai ◽  
Yuki Yamazaki ◽  
Kenta Saito ◽  
...  
Keyword(s):  
Mouse Brain ◽  
Dendritic Spines ◽  
Dendritic Spine ◽  
Cortical Neurons ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Brain Functions ◽  
Spine Development ◽  
Mouse Hippocampus

Proper density and morphology of dendritic spines are important for higher brain functions such as learning and memory. However, our knowledge about molecular mechanisms that regulate the　development and maintenance of dendritic spines is limited. We recently reported that cyclin-dependent kinase 5 (Cdk5) is required for the development and maintenance of dendritic spines of cortical neurons in the mouse brain. Previousin vitrostudies have suggested the involvement of Cdk5 substrates in the formation of dendritic spines; however, their role in spine development has not been testedin vivo. Here, we demonstrate that Cdk5 phosphorylates collapsin response mediator protein 2 (CRMP2) in the dendritic spines of cultured hippocampal neurons andin vivoin the mouse brain. When we eliminated CRMP2 phosphorylation inCRMP2KI/KImice, the densities of dendritic spines significantly decreased in hippocampal CA1 pyramidal neurons in the mouse brain. These results indicate that phosphorylation of CRMP2 by Cdk5 is important for dendritic spine development in cortical neurons in the mouse hippocampus.

scholarly journals High current optogenetic channels for stimulation and inhibition of primary rat cortical neurons

2017 ◽  
Author(s):  
Lei Jin ◽  
Eike Frank Joest ◽  
Wenfang Li ◽  
Shiqiang Gao ◽  
Andreas Offenhäusser ◽  
...  
Keyword(s):  
Neural Development ◽  
Cortical Neurons ◽  
Single Channel ◽  
Chloride Concentration ◽  
Neuronal Firing ◽  
High Current ◽  
Neuronal Inhibition ◽  
Rat Cortical Neurons

AbstractChR2-XXL and GtACR1 are currently the cation and anion ends of the optogenetic single channel current range. These were used in primary rat cortical neurons in vitro to manipulate neuronal firing patterns. ChR2-XXL provides high cation currents via elevated light sensitivity and a prolonged open state. Stimulating ChR2-XXL expressing putative presynaptic neurons induced neurotransmission. Moreover, stable depolarisation block could be generated in single neurons using ChR2-XXL, proving that ChR2-XXL is a promising candidate for in vivo applications of optogenetics, for example to treat peripheral neuropathic pain. We also addressed an anion channelrhodopsin (GtACR1) for the next generation of optogenetic neuronal inhibition in primary rat cortical neurons. GtACR1‘s light-gated chloride conduction was verified in primary neurons and the efficient photoinhibition of action potentials, including spontaneous activity, was shown. Our data also implies that the chloride concentration in neurons decreases during neural development. In both cases, we find surprising applications of these high current channels. For ChR2-XXL inhibition and stimulation are possible, while for GtACR1 the role of Cl−during neural development becomes a new optogenetic target.

Glycine Tranporter-1 Blockade Potentiates NMDA-Mediated Responses in Rat Prefrontal Cortical Neurons In Vitro and In Vivo

2003 ◽  
Vol 89 (2) ◽  
pp. 691-703 ◽  
Author(s):  
Long Chen ◽  
Mark Muhlhauser ◽  
Charles R. Yang
Keyword(s):  
Neural Development ◽  
Cortical Neurons ◽  
Critical Role ◽  
Cell Voltage ◽  
Prefrontal Cortical ◽  
Glycine Transporter ◽  
Excitatory Responses ◽  
Site Stimulation

The N-methyl-d-aspartate (NMDA) receptor (NMDA-R) has pivotal roles in neural development, learning, memory, and synaptic plasticity. Functional impairment of NMDA-R has been implicated in schizophrenia. NMDA-R activation requires glycine to act on the glycine-B (GlyB) site of the NMDA-R as an obligatory co-agonist with glutamate. Extracellular glycine near NMDA-R is regulated effectively by a glial glycine transporter (GlyT1). Using whole-cell voltage-clamp recordings in prefrontal cortex (PFC) slices, we have shown that exogenous GlyB site agonists glycine and d-serine, or a specific GlyT1 inhibitor N[3-(4′-fluorophenyl)-3-(4′-phenylphenoxy)propyl]sarcosine (NFPS) in the presence of exogenous glycine (10 μM), potentiated synaptically evoked NMDA excitatory postsynaptic currents (EPSCs) in vitro. Furthermore, in urethan-anesthetized rats, microiontophoretic NMDA pulses excite single PFC neurons. When these responses were blocked by approximately 50% to approximately 90% on continuous iontophoretic application of the GlyB site, antagonist (+)HA-966, intravenous NFPS (5 mg/kg), or a GlyB site agonist d-serine (50 mg/kg iv) reversed this (+)HA-966 block. NFPS may elevate endogenous glycine levels sufficiently to displace (+)HA-966 from the GlyB sites of the NMDA-R, thus enabling reactivation of the NMDA-Rs by iontophoretic NMDA applications. d-Serine (50–100 mg/kg iv) or NFPS (1–2 mg/kg iv) alone also augmented NMDA-evoked excitatory responses. These data suggest that direct GlyB site stimulation byd-serine, or blockade of GLYT1 to elevate endogenous glycine to act on unsaturated GlyB sites on NMDA-Rs, potentiated NMDA-R-mediated firing responses in rat PFC. Hence, blockade of GlyT1 to elevate glycine near the NMDA-R may activate hypofunctional NMDA-R, which has been implicated to play a critical role in the pathophysiology of schizophrenia.

Sign in / Sign up

Export Citation Format

Share Document