EGF Downregulates Presynaptic Maturation and Suppresses Synapse Formation In Vitro and In Vivo

2022 ◽  
Author(s):  
Nobuyuki Takei ◽  
Daisaku Yokomaku ◽  
Takaho Yamada ◽  
Tadasato Nagano ◽  
Akiyoshi Kakita ◽  
...  
Keyword(s):  
Synapse Formation

Neuromuscular target recognition by a homophilic interaction of connectin cell adhesion molecules in Drosophila

Development ◽  
1997 ◽  
Vol 124 (8) ◽  
pp. 1433-1441 ◽  
Author(s):  
A. Nose ◽  
T. Umeda ◽  
M. Takeichi
Keyword(s):  
Cell Adhesion ◽  
Synapse Formation ◽  
Target Recognition ◽  
Surface Protein ◽  
Transgenic Lines ◽  
A Cell ◽  
Neuromuscular Connectivity ◽  
Recognition Molecule

Drosophila Connectin (CON) is a cell surface protein of the leucine-rich repeat family. During the formation of neuromuscular connectivity, CON is expressed on the surface of a subset of embryonic muscles and on the growth cones and axons of the motoneurons that innervate these muscles, including primarily SNa motoneurons and their synaptic targets (lateral muscles). In vitro, CON can mediate homophilic cell adhesion. In this study, we generated transgenic lines that ectopically expressed CON on all muscles. In the transformant embryos and larvae, SNa motoneurons often inappropriately innervated a neighboring non-target muscle (muscle 12) that ectopically expressed CON. Furthermore, the ectopic synapse formation was dependent on the endogenous CON expression on the SNa motoneurons. These results show that CON can function as an attractive and homophilic target recognition molecule in vivo.

scholarly journals The Rac activator DOCK2 regulates natural killer cell–mediated cytotoxicity in mice through the lytic synapse formation

Blood ◽  
2013 ◽  
Vol 122 (3) ◽  
pp. 386-393 ◽  
Author(s):  
Yusuke Sakai ◽  
Yoshihiko Tanaka ◽  
Toyoshi Yanagihara ◽  
Mayuki Watanabe ◽  
Xuefeng Duan ◽  
...  
Keyword(s):  
Nk Cells ◽  
Synapse Formation ◽  
Bone Marrow Cells ◽  
Killer Cell ◽  
Leukemia Cells ◽  
Histocompatibility Complex ◽  
Key Points ◽  
Nk Receptor

Key Points DOCK2-deficienct NK cells fail to effectively kill leukemia cells in vitro and major histocompatibility complex class I–deficient bone marrow cells in vivo. Activating NK receptor–mediated Rac activation and the lytic synapse formation are severely impaired in DOCK2-deficient NK cells.

scholarly journals Glial imaging during synapse remodeling at the neuromuscular junction

2008 ◽  
Vol 4 (4) ◽  
pp. 319-326 ◽  
Author(s):  
Yi Zuo ◽  
Derron Bishop
Keyword(s):  
Neuromuscular Junction ◽  
Schwann Cells ◽  
Synapse Formation ◽  
Ultrastructural Organization ◽  
Post Injury ◽  
Electron Microscopic ◽  
Cell Dynamics ◽  
Transmission Electron

Glia are an indispensable structural and functional component of the synapse. They modulate synaptic transmission and also play important roles in synapse formation and maintenance. The vertebrate neuromuscular junction (NMJ) is a classic model synapse. Due to its large size, simplicity and accessibility, the NMJ has contributed greatly to our understanding of synapse development and organization. In the past decade, the NMJ has also emerged as an effective model for studying glia–synapse interactions, in part due to the development of various labeling techniques that permit NMJs and associated Schwann cells (the glia at NMJs) to be visualized in vitro and in vivo. These approaches have demonstrated that Schwann cells are actively involved in synapse remodeling both during early development and in post-injury reinnervation. In vivo imaging has also recently been combined with serial section transmission electron microscopic (ssTEM) reconstruction to directly examine the ultrastructural organization of remodeling NMJs. In this review, we focus on the anatomical studies of Schwann cell dynamics and their roles in formation, maturation and remodeling of vertebrate NMJs using the highest temporal and spatial resolution methods currently available.

scholarly journals Epigenetic repression of Wnt receptors in AD: a role for Sirtuin2-induced H4K16ac deacetylation of Frizzled1 and Frizzled7 promoters

2021 ◽  
Author(s):  
Ernest Palomer ◽  
Núria Martin-Flores ◽  
Sarah Jolly ◽  
Patricia Pascual-Vargas ◽  
Stefano Benvegnù ◽  
...  
Keyword(s):  
Synapse Formation ◽  
Late Onset ◽  
Wnt Signalling ◽  
Mrna Levels ◽  
Preclinical Ad ◽  
Synapse Degeneration ◽  
Epigenetic Repression

Growing evidence supports a role for deficient Wnt signalling in synapse degeneration in Alzheimer′s disease (AD). First, the Wnt antagonist DKK1 is elevated in the AD brain and is required for amyloidβ-induced synapse loss. Second, LRP6 Wnt co-receptor is required for synapse integrity and three variants of this receptor are linked to late-onset AD. However, the expression/role of other Wnt signalling components remain poorly explored in AD. Wnt receptors Frizzled1 (Fzd1), Fzd5, Fzd7 and Fzd9 are of particular interest due to their role in synapse formation and plasticity. Our analyses showed that FZD1 and FZD7 mRNA levels were reduced in the hippocampus of human preclinical AD (PAD) cases and in the hAPPNLGF/NLGF mouse model. This transcriptional downregulation was accompanied by reduced levels of the pro-transcriptional histone mark H4K16ac and a concomitant increase of its deacetylase Sirt2 at Fzd1 and Fzd7 promoters in AD. In vitro and in vivo inhibition of Sirt2 rescued Fzd1 and Fzd7 mRNA expression and H4K16ac levels at their promoters. In addition, we showed that Sirt2 recruitment to Fzd1 and Fzd7 promoters is dependent on FoxO1 activity in AD, thus acting as a co-repressor. Finally, we found reduced levels of inhibitory phosphorylation on Sirt2 in nuclear PAD samples and increased levels of the Sirt2 phosphatase PP2C, leading to hyperactive nuclear Sirt2 and favouring Fzd1 and Fzd7 repression in AD. Collectively, our findings define a novel role for nuclear hyperactivated Sirt2 in repressing Fzd1 and Fzd7 expression via H4K16ac deacetylation in AD. We propose Sirt2 as an attractive target to ameliorate AD pathology.

scholarly journals Regional heterogeneity of developing GABAergic interneuron excitation in vivo

2019 ◽  
Author(s):  
Yasunobu Murata ◽  
Matthew T. Colonnese
Keyword(s):  
Synapse Formation ◽  
Critical Role ◽  
Reversal Potential ◽  
Pyramidal Cells ◽  
Gabaergic Neurons ◽  
Network Activity ◽  
Gabaergic Interneuron ◽  
Intact Brain

AbstractGABAergic interneurons are proposed to be critical for early activity and synapse formation by directly exciting, rather than inhibiting, neurons in developing hippocampus and neocortex. However, the role of GABAergic neurons in the generation of neonatal network activity has not been tested in vivo, and recent studies have challenged the excitatory nature of early GABA. By locally manipulating interneuron activity in unanesthetized neonatal mice, we show that GABAergic neurons are indeed excitatory in hippocampus at postnatal-day 3 (P3), and responsible for most of the spontaneous firing of pyramidal cells at that age. Hippocampal interneurons become inhibitory by P7, whereas cortical interneurons are inhibitory at P3 and remain so throughout development. This regional and age heterogeneity is the result of a change in chloride reversal potential as activation of light-gated anion channels expressed in glutamatergic neurons causes firing in hippocampus at P3, but silences it at P7. This study in the intact brain reveals a critical role for GABAergic interneuron excitation in neonatal hippocampus, and a surprising heterogeneity of interneuron function in cortical circuits that was not predicted from in vitro studies.

Foreign connections are formed in vitro by Aplysia californica interneuron L10 and its in vivo followers and non-followers

1990 ◽  
Vol 154 (1) ◽  
pp. 237-255
Author(s):  
D. Kleinfeld ◽  
T. D. Parsons ◽  
F. Raccuia-Behling ◽  
B. M. Salzberg ◽  
A. L. Obaid
Keyword(s):  
Action Potential ◽  
Synapse Formation ◽  
Aplysia Californica ◽  
Inhibitory Connection ◽  
Single Action ◽  
Inhibitory Postsynaptic Potentials ◽  
Neuronal Processes ◽  
Dual Action

Aplysia californica interneurone L10 forms a set of presynaptic connections with many postsynaptic ‘follower’ cells in the abdominal ganglion. These followers do not connect back to L10. The present study tests whether the direction and sign of these connections are obligatory and are reconstructed when neuronal processes regenerate in vitro. L10 was co-cultured with one of six different followers and two non-followers. 1. In vitro connections that preserve the sign of those formed in vivo were made by L10 onto neurones L11, L12 and L13. The connections consisted of inhibitory postsynaptic potentials (IPSPs) with characteristic fast and slow components. 2. In vitro connections that did not preserve the sign of connections found in vivo were made by L10 onto R15, R16 and L7. Neurones R15 and R16 receive excitatory inputs from L10 in vivo and L7 receives a dual-action input in vivo, with inhibition followed by excitation. A purely inhibitory connection from L10 was formed in vitro onto all these cells. 3. Connections that have never been observed in vivo in terms of both direction and sign were formed in vitro. Followers L7, L11, L12, L13 and R16 and non-follower L14A formed novel connections onto L10. All these connections were inhibitory and some were strong. For example, IPSPs with a magnitude of 20 mV were observed in L10 following a single action potential in L13. Our results show that identified Aplysia neurones can form stereotyped specific connections in vitro. The specificity is different from that in the intact ganglion. The ubiquity of novel connections suggests that restrictions imposed on synaptogenesis in the animal are distinct from those regulating synapse formation in culture.

scholarly journals Neuromodulation of excitatory synaptogenesis in striatal development

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Yevgenia Kozorovitskiy ◽  
Rui Peixoto ◽  
Wengang Wang ◽  
Arpiar Saunders ◽  
Bernardo L Sabatini
Keyword(s):  
Developmental Plasticity ◽  
Synapse Formation ◽  
Glutamate Release ◽  
Projection Neurons ◽  
Excitatory Synapses ◽  
Indirect Pathway ◽  
Protein Receptors ◽  
In Vivo Effects

Dopamine is released in the striatum during development and impacts the activity of Protein Kinase A (PKA) in striatal spiny projection neurons (SPNs). We examined whether dopaminergic neuromodulation regulates activity-dependent glutamatergic synapse formation in the developing striatum. Systemic in vivo treatment with Gαs-coupled G-protein receptors (GPCRs) agonists enhanced excitatory synapses on direct pathway striatal spiny projection neurons (dSPNs), whereas rapid production of excitatory synapses on indirect pathway neurons (iSPNs) required the activation of Gαs GPCRs in SPNs of both pathways. Nevertheless, in vitro Gαs activation was sufficient to enhance spinogenesis induced by glutamate photolysis in both dSPNs and iSPNs, suggesting that iSPNs in intact neural circuits have additional requirements for rapid synaptic development. We evaluated the in vivo effects of enhanced glutamate release from corticostriatal axons and postsynaptic PKA and discovered a mechanism of developmental plasticity wherein rapid synaptogenesis is promoted by the coordinated actions of glutamate and postsynaptic Gαs-coupled receptors.

scholarly journals Loss of MeCP2 disrupts cell autonomous and autocrine BDNF signaling in mouse glutamatergic neurons

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Charanya Sampathkumar ◽  
Yuan-Ju Wu ◽  
Mayur Vadhvani ◽  
Thorsten Trimbuch ◽  
Britta Eickholt ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Target Genes ◽  
Synapse Formation ◽  
Neurodevelopmental Disorder ◽  
Glutamatergic Neurons ◽  
Trkb Receptors ◽  
Wide Range ◽  
Bdnf Signaling

Mutations in the MECP2 gene cause the neurodevelopmental disorder Rett syndrome (RTT). Previous studies have shown that altered MeCP2 levels result in aberrant neurite outgrowth and glutamatergic synapse formation. However, causal molecular mechanisms are not well understood since MeCP2 is known to regulate transcription of a wide range of target genes. Here, we describe a key role for a constitutive BDNF feed forward signaling pathway in regulating synaptic response, general growth and differentiation of glutamatergic neurons. Chronic block of TrkB receptors mimics the MeCP2 deficiency in wildtype glutamatergic neurons, while re-expression of BDNF quantitatively rescues MeCP2 deficiency. We show that BDNF acts cell autonomous and autocrine, as wildtype neurons are not capable of rescuing growth deficits in neighboring MeCP2 deficient neurons in vitro and in vivo. These findings are relevant for understanding RTT pathophysiology, wherein wildtype and mutant neurons are intermixed throughout the nervous system.

scholarly journals Nanoscale patterning of in vitro neuronal circuits

2021 ◽  
Author(s):  
János Vörös ◽  
Sean Weaver ◽  
Jose C. Mateus ◽  
Paulo Aguiar ◽  
Dirk van Swaay ◽  
...  
Keyword(s):  
Computational Models ◽  
Synapse Formation ◽  
Ex Vivo ◽  
Axon Growth ◽  
Neuronal Circuits ◽  
Calcium Indicator ◽  
The Difference ◽  
Pass Through

Methods for patterning neurons in vitro have gradually improved and are used to investigate questions difficult to address in or ex vivo. Though these techniques guide axons between groups of neurons, multiscale control of neuronal connectivity, from circuits to synapses, is yet to be achieved in vitro. As studying neuronal circuits with synaptic resolution in vivo poses significant challenges, an in vitro alternative could serve as a testbed for in vivo experiments or as a platform for validating biophysical and computational models. In this work we use a combination of electron beam and photolithography to create polydimethylsiloxane (PDMS) structures with features ranging from 150 nanometers to a few millimeters. Leveraging the difference between average axon and dendritic spine diameters, we restrict axon growth while allowing spines to pass through nanochannels to guide synapse formation between small groups of neurons (i.e. nodes). We show this technique can be used to generate large numbers of isolated feed-forward circuits where connections between nodes are restricted to regions connected by nanochannels. Using a genetically encoded calcium indicator in combination with fluorescently tagged post synaptic protein, PSD-95, we demonstrate functional synapses can form in this region. Although more work needs to be done to control connectivity in vitro, we believe this is a significant step in that direction.

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