scholarly journals Transsynaptic N-cadherin adhesion complexes control presynaptic vesicle and bulk endocytosis at physiological temperature

2021 ◽  
Author(s):  
Sushma Dagar ◽  
Kurt Gottmann
Keyword(s):  
Actin Polymerization ◽  
Super Resolution ◽  
Glutamatergic Synapses ◽  
Physiological Regulation ◽  
Adhesion Protein ◽  
Physiological Temperature ◽  
Presynaptic Vesicle ◽  
Efficient Coupling ◽  
And Function ◽  
Homophilic Adhesion

AbstractAt mammalian glutamatergic synapses, most basic elements of synaptic transmission have been shown to be modulated by specific transsynaptic adhesion complexes. However, although crucial for synapse homeostasis, a physiological regulation of synaptic vesicle endocytosis by adhesion molecules has not been firmly established. The homophilic adhesion protein N-cadherin is localized at the peri-active zone, where the highly temperature dependent endocytosis of vesicles occurs. Here, we demonstrate an important modulatory role of N-cadherin in endocytosis at near physiological temperature by synaptophysin-pHluorin imaging. Different modes of endocytosis including bulk endocytosis were dependent on N-cadherin expression and function. N-cadherin modulation was mediated by actin filaments, because actin polymerization rescued the knockout induced endocytosis defect. Using super-resolution imaging, we found a strong recruitment of N-cadherin to glutamatergic synapses upon massive vesicle release, which might in turn enhance vesicle endocytosis. This provides a novel, adhesion protein mediated mechanism for efficient coupling of exo- and endocytosis.

scholarly journals Transsynaptic N-Cadherin Adhesion Complexes Control Presynaptic Vesicle and Bulk Endocytosis at Physiological Temperature

2021 ◽  
Vol 15 ◽  
Author(s):  
Sushma Dagar ◽  
Zenghui Teng ◽  
Kurt Gottmann
Keyword(s):  
Actin Polymerization ◽  
Super Resolution ◽  
Glutamatergic Synapses ◽  
Physiological Regulation ◽  
Adhesion Protein ◽  
Physiological Temperature ◽  
Presynaptic Vesicle ◽  
Efficient Coupling ◽  
And Function ◽  
Homophilic Adhesion

At mammalian glutamatergic synapses, most basic elements of synaptic transmission have been shown to be modulated by specific transsynaptic adhesion complexes. However, although crucial for synapse homeostasis, a physiological regulation of synaptic vesicle endocytosis by adhesion molecules has not been firmly established. The homophilic adhesion protein N-cadherin is localized at the peri-active zone, where the highly temperature-dependent endocytosis of vesicles occurs. Here, we demonstrate an important modulatory role of N-cadherin in endocytosis at near physiological temperature by synaptophysin-pHluorin imaging. Different modes of endocytosis including bulk endocytosis were dependent on N-cadherin expression and function. N-cadherin modulation might be mediated by actin filaments because actin polymerization ameliorated the knockout-induced endocytosis defect. Using super-resolution imaging, we found strong recruitment of N-cadherin to glutamatergic synapses upon massive vesicle release, which might in turn enhance vesicle endocytosis. This provides a novel, adhesion protein-mediated mechanism for efficient coupling of exo- and endocytosis.

scholarly journals The adhesion protein IgSF9b is coupled to neuroligin 2 via S-SCAM to promote inhibitory synapse development

2013 ◽  
Vol 201 (6) ◽  
pp. 929-944 ◽  
Author(s):  
Jooyeon Woo ◽  
Seok-Kyu Kwon ◽  
Jungyong Nam ◽  
Seungwon Choi ◽  
Hideto Takahashi ◽  
...  
Keyword(s):  
Adhesion Molecules ◽  
Adhesion Molecule ◽  
Synapse Formation ◽  
Super Resolution ◽  
Protein S ◽  
Inhibitory Synapses ◽  
Synaptic Organization ◽  
Adhesion Protein ◽  
Resolution Imaging ◽  
Homophilic Adhesion

Synaptic adhesion molecules regulate diverse aspects of synapse formation and maintenance. Many known synaptic adhesion molecules localize at excitatory synapses, whereas relatively little is known about inhibitory synaptic adhesion molecules. Here we report that IgSF9b is a novel, brain-specific, homophilic adhesion molecule that is strongly expressed in GABAergic interneurons. IgSF9b was preferentially localized at inhibitory synapses in cultured rat hippocampal and cortical interneurons and was required for the development of inhibitory synapses onto interneurons. IgSF9b formed a subsynaptic domain distinct from the GABAA receptor– and gephyrin-containing domain, as indicated by super-resolution imaging. IgSF9b was linked to neuroligin 2, an inhibitory synaptic adhesion molecule coupled to gephyrin, via the multi-PDZ protein S-SCAM. IgSF9b and neuroligin 2 could reciprocally cluster each other. These results suggest a novel mode of inhibitory synaptic organization in which two subsynaptic domains, one containing IgSF9b for synaptic adhesion and the other containing gephyrin and GABAA receptors for synaptic transmission, are interconnected through S-SCAM and neuroligin 2.

scholarly journals Vasoconstrictor-induced endocytic recycling regulates focal adhesion protein localization and function in vascular smooth muscle

2013 ◽  
Vol 305 (2) ◽  
pp. C215-C227 ◽  
Author(s):  
Ransom H. Poythress ◽  
Cynthia Gallant ◽  
Susanne Vetterkind ◽  
Kathleen G. Morgan
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Actin Polymerization ◽  
Protein Localization ◽  
Focal Adhesions ◽  
Significant Inhibition ◽  
Adhesion Protein ◽  
Endosomal Recycling ◽  
Focal Adhesion Protein ◽  
And Function

Turnover of focal adhesions (FAs) is known to be critical for cell migration and adhesion of proliferative vascular smooth muscle (VSM) cells. However, it is often assumed that FAs in nonmigratory, differentiated VSM (dVSM) cells embedded in the wall of healthy blood vessels are stable structures. Recent work has demonstrated agonist-induced actin polymerization and Src-dependent FA phosphorylation in dVSM cells, suggesting that agonist-induced FA remodeling occurs. However, the mechanisms and extent of FA remodeling are largely unknown in dVSM. Here we show, for the first time, that a distinct subpopulation of dVSM FA proteins, but not the entire FA, remodels in response to the α-agonist phenylephrine. Vasodilator-stimulated phosphoprotein and zyxin displayed the largest redistributions, while β-integrin and FA kinase showed undetectable redistribution. Vinculin, metavinculin, Src, Crk-associated substrate, and paxillin displayed intermediate degrees of redistribution. Redistributions into membrane fractions were especially prominent, suggesting endosomal mechanisms. Deconvolution microscopy, quantitative colocalization analysis, and Duolink proximity ligation assays revealed that phenylephrine increases the association of FA proteins with early endosomal markers Rab5 and early endosomal antigen 1. Endosomal disruption with the small-molecule inhibitor primaquine inhibits agonist-induced redistribution of FA proteins, confirming endosomal recycling. FA recycling was also inhibited by cytochalasin D, latrunculin B, and colchicine, indicating that the redistribution is actin- and microtubule-dependent. Furthermore, inhibition of endosomal recycling causes a significant inhibition of the rate of development of agonist-induced dVSM contractions. Thus these studies are consistent with the concept that FAs in dVSM cells, embedded in the wall of the aorta, remodel during the action of a vasoconstrictor.

Super-Resolution Microscopy in Studying the Structure and Function of the Cell Nucleus

Acta Naturae ◽  
2017 ◽  
Vol 9 (4) ◽  
pp. 42-51
Author(s):  
S. S. Ryabichko ◽  
◽  
A. N. Ibragimov ◽  
L. A. Lebedeva ◽  
E. N. Kozlov ◽  
...  
Keyword(s):  
Cell Nucleus ◽  
Super Resolution ◽  
Structure And Function ◽  
And Function ◽  
Super Resolution Microscopy

scholarly journals Mice with cleavage-resistant N-cadherin exhibit synapse anomaly in the hippocampus and outperformance in spatial learning tasks

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
M. Asada-Utsugi ◽  
K. Uemura ◽  
M. Kubota ◽  
Y. Noda ◽  
Y. Tashiro ◽  
...  
Keyword(s):  
Memory Function ◽  
Three Dimensional ◽  
Excitatory Synapses ◽  
Missense Mutations ◽  
Glutamatergic Synapses ◽  
Learning Tasks ◽  
Transmission Electron ◽  
Nmdar Activation ◽  
And Function

AbstractN-cadherin is a homophilic cell adhesion molecule that stabilizes excitatory synapses, by connecting pre- and post-synaptic termini. Upon NMDA receptor (NMDAR) activation by glutamate, membrane-proximal domains of N-cadherin are cleaved serially by a-disintegrin-and-metalloprotease 10 (ADAM10) and then presenilin 1(PS1, catalytic subunit of the γ-secretase complex). To assess the physiological significance of the initial N-cadherin cleavage, we engineer the mouse genome to create a knock-in allele with tandem missense mutations in the mouse N-cadherin/Cadherin-2 gene (Cdh2R714G, I715D, or GD) that confers resistance on proteolysis by ADAM10 (GD mice). GD mice showed a better performance in the radial maze test, with significantly less revisiting errors after intervals of 30 and 300 s than WT, and a tendency for enhanced freezing in fear conditioning. Interestingly, GD mice reveal higher complexity in the tufts of thorny excrescence in the CA3 region of the hippocampus. Fine morphometry with serial section transmission electron microscopy (ssTEM) and three-dimensional (3D) reconstruction reveals significantly higher synaptic density, significantly smaller PSD area, and normal dendritic spine volume in GD mice. This knock-in mouse has provided in vivo evidence that ADAM10-mediated cleavage is a critical step in N-cadherin shedding and degradation and involved in the structure and function of glutamatergic synapses, which affect the memory function.

Cardiac expression of a gain-of-function α5-integrin results in perinatal lethality

2001 ◽  
Vol 280 (1) ◽  
pp. H361-H367 ◽  
Author(s):  
Maria L. Valencik ◽  
John A. McDonald
Keyword(s):  
Cardiac Development ◽  
Wild Type ◽  
Integrin Receptors ◽  
Gain Of Function ◽  
Transgenic Expression ◽  
Physiological Regulation ◽  
Myocyte Differentiation ◽  
Perinatal Lethality ◽  
And Function

Communication between the extracellular matrix and the intracellular signal transduction and cytoskeletal system is mediated by integrin receptors. α5β1-Integrin and its cognate ligand fibronectin are essential in development of mesodermal structures, myocyte differentiation, and normal cardiac development. To begin to explore the potential roles of α5β1-integrin specifically in cardiomyocytes, we used a transgenic expression strategy. We overexpressed two forms of the human α5-integrin in cardiomyocytes: the full-length wild-type α5-integrin and a putative gain-of-function mutation created by truncating the cytoplasmic domain, designated α5-1-integrin. Overexpression of the wild-type α5-integrin has no detectable adverse effects in the mouse, whereas expression of α5-1-integrin caused electrocardiographic abnormalities, fibrotic changes in the ventricle, and perinatal lethality. Thus physiological regulation of integrin function appears essential for maintenance of normal cardiomyocyte structure and function. This strengthens the role of inside-out signaling in regulation of integrins in vivo and suggests that integrins and associated signaling molecules are important in cardiomyocyte function.

scholarly journals TORC2-Gad8-dependent myosin phosphorylation modulates regulation by calcium

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Karen Baker ◽  
Irene A Gyamfi ◽  
Gregory I Mashanov ◽  
Justin E Molloy ◽  
Michael A Geeves ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Cell Cycle Progression ◽  
Actin Polymerization ◽  
Neck Region ◽  
Signaling Networks ◽  
Tor Signaling ◽  
Multicellular Development ◽  
Membrane Reorganization ◽  
And Function

Cells respond to changes in their environment through signaling networks that modulate cytoskeleton and membrane organization to coordinate cell-cycle progression, polarized cell growth and multicellular development. Here, we define a novel regulatory mechanism by which the motor activity and function of the fission yeast type one myosin, Myo1, is modulated by TORC2-signalling-dependent phosphorylation. Phosphorylation of the conserved serine at position 742 (S742) within the neck region changes both the conformation of the neck region and the interactions between Myo1 and its associating calmodulin light chains. S742 phosphorylation thereby couples the calcium and TOR signaling networks that are involved in the modulation of myosin-1 dynamics to co-ordinate actin polymerization and membrane reorganization at sites of endocytosis and polarised cell growth in response to environmental and cell-cycle cues.

scholarly journals Heparan sulfate molecules mediate synapse formation and function of male mating neural circuits in C. elegans

2018 ◽  
Author(s):  
María I. Lázaro-Peña ◽  
Carlos A. Díaz-Balzac ◽  
Hannes E. Bülow ◽  
Scott W. Emmons
Keyword(s):  
Nervous System ◽  
Cell Adhesion ◽  
Neural Cell ◽  
Male Mating ◽  
Synaptic Connections ◽  
Adhesion Protein ◽  
C Elegans ◽  
Neural Cell Adhesion ◽  
Heparan Sulfates ◽  
And Function

AbstractThe nervous system regulates complex behaviors through a network of neurons interconnected by synapses. How specific synaptic connections are genetically determined is still unclear. Male mating is the most complex behavior in C. elegans. It is composed of sequential steps that are governed by more than 3,000 chemical connections. Here we show that heparan sulfates (HS) play a role in the formation and function of the male neural network. Cell-autonomous and non-autonomous 3-O sulfation by the HS modification enzyme HST-3.1/HS 3-O-sulfotransferase, localized to the HSPG glypicans LON-2/glypican and GPN-1/glypican, was specifically required for response to hermaphrodite contact during mating. Loss of 3-O sulfation resulted in the presynaptic accumulation of RAB-3, a molecule that localizes to synaptic vesicles, disrupting the formation of synapses in a component of the mating circuits. We also show that neural cell adhesion protein neurexin promotes and neural cell adhesion protein neuroligin inhibits formation of the same set of synapses in a parallel pathway. Thus, neural cell adhesion proteins and extracellular matrix components act together in the formation of synaptic connections.Author SummaryThe formation of the nervous system requires the function of several genetically-encoded proteins to form complex networks. Enzymatically-generated modifications of these proteins play a crucial role during this process. These authors analyzed the role of heparan sulfates in the process of synaptogenesis in the male tail of C. elegans. A modification of heparan sulfate is required for the formation of specific synapses between neurons by acting cell-autonomously and non-autonomously. Could it be that heparan sulfates and their diverse modifications are a component of the specification factor that neurons use to make such large numbers of connections unique?

scholarly journals Adult medial habenula neurons require GDNF receptor GFRα1 for synaptic stability and function

PLoS Biology ◽  
2021 ◽  
Vol 19 (11) ◽  
pp. e3001350
Author(s):  
Diana Fernández-Suárez ◽  
Favio A. Krapacher ◽  
Katarzyna Pietrajtis ◽  
Annika Andersson ◽  
Lilian Kisiswa ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Proximity Ligation Assay ◽  
Glutamatergic Synapses ◽  
Proximity Ligation ◽  
Postsynaptic Currents ◽  
Adult Mice ◽  
Medial Habenula ◽  
Factor Receptor Alpha ◽  
And Function ◽  
Anxiety And Fear

The medial habenula (mHb) is an understudied small brain nucleus linking forebrain and midbrain structures controlling anxiety and fear behaviors. The mechanisms that maintain the structural and functional integrity of mHb neurons and their synapses remain unknown. Using spatiotemporally controlled Cre-mediated recombination in adult mice, we found that the glial cell–derived neurotrophic factor receptor alpha 1 (GFRα1) is required in adult mHb neurons for synaptic stability and function. mHb neurons express some of the highest levels of GFRα1 in the mouse brain, and acute ablation of GFRα1 results in loss of septohabenular and habenulointerpeduncular glutamatergic synapses, with the remaining synapses displaying reduced numbers of presynaptic vesicles. Chemo- and optogenetic studies in mice lacking GFRα1 revealed impaired circuit connectivity, reduced AMPA receptor postsynaptic currents, and abnormally low rectification index (R.I.) of AMPARs, suggesting reduced Ca2+ permeability. Further biochemical and proximity ligation assay (PLA) studies defined the presence of GluA1/GluA2 (Ca2+ impermeable) as well as GluA1/GluA4 (Ca2+ permeable) AMPAR complexes in mHb neurons, as well as clear differences in the levels and association of AMPAR subunits with mHb neurons lacking GFRα1. Finally, acute loss of GFRα1 in adult mHb neurons reduced anxiety-like behavior and potentiated context-based fear responses, phenocopying the effects of lesions to septal projections to the mHb. These results uncover an unexpected function for GFRα1 in the maintenance and function of adult glutamatergic synapses and reveal a potential new mechanism for regulating synaptic plasticity in the septohabenulointerpeduncular pathway and attuning of anxiety and fear behaviors.

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