scholarly journals Retrograde transport of Akt by a neuronal Rab5-APPL1 endosome

2018 ◽  
Author(s):  
Livia Goto-Silva ◽  
Marisa P. McShane ◽  
Sara Salinas ◽  
Yannis Kalaidzidis ◽  
Giampietro Schiavo ◽  
...  
Keyword(s):  
Long Range ◽  
Critical Role ◽  
Primary Cultures ◽  
Pyramidal Cells ◽  
Retrograde Transport ◽  
Small Gtpase ◽  
Neurotrophin Receptor ◽  
Dependent Manner ◽  
Long Distance ◽  
Hippocampal Pyramidal Cells

AbstractLong-distance axonal trafficking plays a critical role in neuronal function, and transport defects have been linked to neurodegenerative disorders. Various lines of evidence suggest that the small GTPase Rab5 plays a role in neuronal signaling via early endosomal transport. Here, we characterized the motility of Rab5 endosomes in primary cultures of mouse hippocampal pyramidal cells by live-cell imaging and showed that they exhibit bi-directional long-range motility in axons, with a strong bias toward retrograde transport. Characterization of key Rab5 effectors revealed that endogenous Rabankyrin-5, Rabenosyn-5 and APPL1 are all present in axons. Further analysis of APPL1-positive endosomes showed that, similar to Rab5-endosomes, they display more frequent long-range retrograde than anterograde movement, with the endosomal levels of APPL1 correlated with faster retrograde movement. Interestingly, APPL1-endosomes transport the neurotrophin receptor TrkB and mediate retrograde axonal transport of the kinase Akt1. FRET analysis revealed that APPL1 and Akt1 interact in an endocytosis-dependent manner. We conclude that Rab5-APPL1 endosomes exhibit the hallmarks of axonal signaling endosomes to transport Akt1 in hippocampal pyramidal cells.

Magnitude-dependent regulation of pulmonary endothelial cell barrier function by cyclic stretch

2003 ◽  
Vol 285 (4) ◽  
pp. L785-L797 ◽  
Author(s):  
Konstantin G. Birukov ◽  
Jeffrey R. Jacobson ◽  
Alejandro A. Flores ◽  
Shui Q. Ye ◽  
Anna A. Birukova ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Map Kinases ◽  
Critical Role ◽  
Barrier Properties ◽  
Small Gtpase ◽  
Cyclic Stretch ◽  
Cell Permeability ◽  
Dependent Manner ◽  
Sphingosine 1 Phosphate ◽  
Mlc Phosphorylation

Ventilator-induced lung injury syndromes are characterized by profound increases in vascular leakiness and activation of inflammatory processes. To explore whether excessive cyclic stretch (CS) directly causes vascular barrier disruption or enhances endothelial cell sensitivity to edemagenic agents, human pulmonary artery endothelial cells (HPAEC) were exposed to physiologically (5% elongation) or pathologically (18% elongation) relevant levels of strain. CS produced rapid (10 min) increases in myosin light chain (MLC) phosphorylation, activation of p38 and extracellular signal-related kinase 1/2 MAP kinases, and actomyosin remodeling. Acute (15 min) and chronic (48 h) CS markedly enhanced thrombin-induced MLC phosphorylation (2.1-fold and 3.2-fold for 15-min CS at 5 and 18% elongation and 2.1-fold and 3.1-fold for 48-h CS at 5 and 18% elongation, respectively). HPAEC preconditioned at 18% CS, but not at 5% CS, exhibited significantly enhanced thrombin-induced reduction in transendothelial electrical resistance but did not affect barrier protective effect of sphingosine-1-phosphate (0.5 μM). Finally, expression profiling analysis revealed a number of genes, including small GTPase rho, apoptosis mediator ZIP kinase, and proteinase activated receptor-2, to be regulated by CS in an amplitude-dependent manner. Thus our study demonstrates a critical role for the magnitude of CS in regulation of agonist-mediated pulmonary endothelial cell permeability and strongly suggests phenotypic regulation of HPAEC barrier properties by CS.

scholarly journals Impaired long-range synchronization of gamma oscillations in the neocortex of a mouse lacking Kv3.2 potassium channels

2012 ◽  
Vol 108 (3) ◽  
pp. 827-833 ◽  
Author(s):  
Michael Harvey ◽  
David Lau ◽  
Eugene Civillico ◽  
Bernardo Rudy ◽  
Diego Contreras
Keyword(s):  
Long Range ◽  
High Frequency ◽  
Single Cells ◽  
Critical Role ◽  
Pyramidal Cells ◽  
Gamma Oscillations ◽  
Network Activity ◽  
Inhibitory Interneurons ◽  
Phase Lag ◽  
Firing Properties

Inhibitory interneurons play a critical role in the generation of gamma (20–50 Hz) oscillations, either by forming mutually inhibitory networks or as part of recurrent networks with pyramidal cells. A key property of fast spiking interneurons is their ability to generate brief spikes and high-frequency spike trains with little accommodation. However, the role of their firing properties in network oscillations has not been tested in vivo. Studies in hippocampus in vitro have shown that high-frequency spike doublets in interneurons play a key role in the long-range synchronization of gamma oscillations with little phase lag despite long axonal conduction delays. We generated a knockout (KO) mouse lacking Kv3.2 potassium channel subunits, where infragranular inhibitory interneurons lose the ability both to sustain high-frequency firing and reliably generate high-frequency spike doublets. We recorded cortical local field potentials in anesthetized and awake, restrained mice. Spontaneous activity of the KO and the wild-type (WT) showed similar content of gamma and slow (0.1–15 Hz) frequencies, but the KO showed a significantly larger decay of synchronization of gamma oscillations with distance. Coronal cuts in the cortex of WT mice decreased synchronization to values similar to the intact KO. The synchronization of the slow oscillation showed little decay with distance in both mice and was largely reduced after coronal cuts. Our results show that the firing properties of inhibitory interneurons are critical for long-range synchronization of gamma oscillations, and emphasize that intrinsic electrophysiological properties of single cells may play a key role in the spatiotemporal characteristics of network activity.

scholarly journals Ontogeny of the VIP+ interneuron sensory-motor circuit prior to active whisking

2020 ◽  
Author(s):  
Cristiana Vagnoni ◽  
Liad J. Baruchin ◽  
Filippo Ghezzi ◽  
Sara Ratti ◽  
Zoltán Molnár ◽  
...  
Keyword(s):  
Long Range ◽  
Critical Role ◽  
Pyramidal Cells ◽  
Cortical Circuits ◽  
Motor Processing ◽  
Efferent Connections ◽  
Sensory Motor ◽  
Sensory Evoked ◽  
Inside Out

ABSTRACTDevelopment of the cortical circuits for sensory-motor processing require the coordinated integration of both columnar and long-range synaptic connections. To understand how this occurs at the level of individual neurons we have explored the timeline over which vasoactive intestinal peptide (VIP)-expressing interneurons integrate into mouse somatosensory cortex. We find a distinction in emergent long-range anterior-motor and columnar glutamatergic inputs onto layer (L)2 and L3 VIP+ interneurons respectively. In parallel, VIP+ interneurons form efferent connections onto both pyramidal cells and interneurons in the immediate column in an inside-out manner. Cell-autonomous deletion of the fate-determinant transcription factor, Prox1, spares long-range anterior-motor inputs onto VIP+ interneurons, but leads to deficits in local connectivity. This imbalance in the somatosensory circuit results in altered spontaneous and sensory-evoked cortical activity in vivo. This identifies a critical role for VIP+ interneurons, and more broadly interneuron heterogeneity, in formative circuits of neocortex.

scholarly journals Rab2 drives axonal transport of dense core vesicles and lysosomal organelles

2020 ◽  
Author(s):  
Viktor K. Lund ◽  
Matthew D. Lycas ◽  
Anders Schack ◽  
Rita C. Andersen ◽  
Ulrik Gether ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Long Range ◽  
Molecular Motors ◽  
Critical Role ◽  
Model System ◽  
Small Gtpase ◽  
Dense Core ◽  
Fast Axonal Transport ◽  
Dense Core Vesicles ◽  
Motility Factor

SUMMARYLong range fast axonal transport of neuropeptide-containing dense core vesicles (DCVs), endolysosomal organelles and presynaptic components is critical for maintaining the functionality of neurons. How the transport of DCVs is orchestrated remains an important unresolved question. The small GTPase Rab2 has previously been shown to mediate DCV biogenesis and endosome-lysosome fusion. Here we use the Drosophila model system to demonstrate that Rab2 also plays a critical role in bidirectional axonal transport of DCVs, endosomes and lysosomal organelles, most likely by controlling molecular motors. We further show that the lysosomal motility factor Arl8 is required as well for axonal transport of DCVs, but unlike Rab2 is also critical for DCV exit from cell bodies into axons. Our results uncover the mechanisms responsible for axonal transport of DCVs and reveal surprising parallels between the regulation of DCVs and lysosomal motility.

scholarly journals A Neural Mass Model to Simulate Different Rhythms in a Cortical Region

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
M. Zavaglia ◽  
F. Cona ◽  
M. Ursino
Keyword(s):  
Long Range ◽  
Critical Role ◽  
Experimental Studies ◽  
Pyramidal Cells ◽  
Neural Mass Model ◽  
Cortical Region ◽  
Eeg Rhythms ◽  
Mass Model ◽  
Neural Mass ◽  
Neural Populations

An original neural mass model of a cortical region has been used to investigate the origin of EEG rhythms. The model consists of four interconnected neural populations: pyramidal cells, excitatory interneurons and inhibitory interneurons with slow and fast synaptic kinetics, and respectively. A new aspect, not present in previous versions, consists in the inclusion of a self-loop among interneurons. The connectivity parameters among neural populations have been changed in order to reproduce different EEG rhythms. Moreover, two cortical regions have been connected by using different typologies of long range connections. Results show that the model of a single cortical region is able to simulate the occurrence of multiple power spectral density (PSD) peaks; in particular the new inhibitory loop seems to have a critical role in the activation in gamma () band, in agreement with experimental studies. Moreover the effect of different kinds of connections between two regions has been investigated, suggesting that long range connections toward interneurons have a major impact than connections toward pyramidal cells. The model can be of value to gain a deeper insight into mechanisms involved in the generation of rhythms and to provide better understanding of cortical EEG spectra.

scholarly journals Regulation of Protein Transport from the Golgi Complex to the Endoplasmic Reticulum by CDC42 and N-WASP

2002 ◽  
Vol 13 (3) ◽  
pp. 866-879 ◽  
Author(s):  
Ana Luna ◽  
Olga B. Matas ◽  
José Angel Martı́nez-Menárguez ◽  
Eugenia Mato ◽  
Juan M. Durán ◽  
...  
Keyword(s):  
Golgi Complex ◽  
Mammalian Cells ◽  
Protein Transport ◽  
Retrograde Transport ◽  
Small Gtpase ◽  
Actin Dynamics ◽  
Mutant Form ◽  
Dependent Manner ◽  
Wild Type ◽  
Kdel Receptor

Actin is involved in the organization of the Golgi complex and Golgi-to-ER protein transport in mammalian cells. Little, however, is known about the regulation of the Golgi-associated actin cytoskeleton. We provide evidence that Cdc42, a small GTPase that regulates actin dynamics, controls Golgi-to-ER protein transport. We located GFP-Cdc42 in the lateral portions of Golgi cisternae and in COPI-coated and noncoated Golgi-associated transport intermediates. Overexpression of Cdc42 and its activated form Cdc42V12 inhibited the retrograde transport of Shiga toxin from the Golgi complex to the ER, the redistribution of the KDEL receptor, and the ER accumulation of Golgi-resident proteins induced by the active GTP-bound mutant of Sar1 (Sar1[H79G]). Coexpression of wild-type or activated Cdc42 and N-WASP also inhibited Golgi-to-ER transport, but this was not the case in cells expressing Cdc42V12 and N-WASP(ΔWA), a mutant form of N-WASP that lacks Arp2/3 binding. Furthermore, Cdc42V12 recruited GFP-N-WASP to the Golgi complex. We therefore conclude that Cdc42 regulates Golgi-to-ER protein transport in an N-WASP–dependent manner.

scholarly journals Interleukin 1β Regulation of the System xc− Substrate-specific Subunit, xCT, in Primary Mouse Astrocytes Involves the RNA-binding Protein HuR

2015 ◽  
Vol 291 (4) ◽  
pp. 1643-1651 ◽  
Author(s):  
Jingxue Shi ◽  
Yan He ◽  
Sandra J. Hewett ◽  
James A. Hewett
Keyword(s):  
Half Life ◽  
Rna Binding ◽  
Critical Role ◽  
Primary Cultures ◽  
Dependent Manner ◽  
Protein Levels ◽  
Mouse Cortex ◽  
Primary Mouse ◽  
Rna Immunoprecipitation ◽  
Mrna Half Life

System xc− is a heteromeric amino acid cystine/glutamate antiporter that is constitutively expressed by cells of the CNS, where it functions in the maintenance of intracellular glutathione and extracellular glutamate levels. We recently determined that the cytokine, IL-1β, increases the activity of system xc− in CNS astrocytes secondary to an up-regulation of its substrate-specific light chain, xCT, and that this occurs, in part, at the level of transcription. However, an in silico analysis of the murine xCT 3′-UTR identified numerous copies of adenine- and uridine-rich elements, raising the possibility that undefined trans-acting factors governing mRNA stability and translation may also contribute to xCT expression. Here we show that IL-1β increases the level of mRNA encoding xCT in primary cultures of astrocytes isolated from mouse cortex in association with an increase in xCT mRNA half-life. Additionally, IL-1β induces HuR translocation from the nucleus to the cytoplasm. RNA immunoprecipitation analysis reveals that HuR binds directly to the 3′-UTR of xCT in an IL-1β-dependent manner. Knockdown of endogenous HuR protein abrogates the IL-1β-mediated increase in xCT mRNA half-life, whereas overexpression of HuR in unstimulated primary mouse astrocytes doubles the half-life of constitutive xCT mRNA. This latter effect is accompanied by an increase in xCT protein levels, as well as a functional increase in system xc− activity. Altogether, these data support a critical role for HuR in mediating the IL-1β-induced stabilization of astrocyte xCT mRNA.

scholarly journals CAP1 binds and activates adenylyl cyclase in mammalian cells

2021 ◽  
Vol 118 (24) ◽  
pp. e2024576118
Author(s):  
Xuefeng Zhang ◽  
Alejandro Pizzoni ◽  
Kyoungja Hong ◽  
Nyla Naim ◽  
Chao Qi ◽  
...  
Keyword(s):  
Adenylyl Cyclase ◽  
Mammalian Cells ◽  
Feedback Loop ◽  
Critical Role ◽  
Small Gtpase ◽  
Actin Dynamics ◽  
Live Cells ◽  
Dependent Manner ◽  
Downstream Effector

CAP1 (Cyclase-Associated Protein 1) is highly conserved in evolution. Originally identified in yeast as a bifunctional protein involved in Ras-adenylyl cyclase and F-actin dynamics regulation, the adenylyl cyclase component seems to be lost in mammalian cells. Prompted by our recent identification of the Ras-like small GTPase Rap1 as a GTP-independent but geranylgeranyl-specific partner for CAP1, we hypothesized that CAP1-Rap1, similar to CAP-Ras-cyclase in yeast, might play a critical role in cAMP dynamics in mammalian cells. In this study, we report that CAP1 binds and activates mammalian adenylyl cyclase in vitro, modulates cAMP in live cells in a Rap1-dependent manner, and affects cAMP-dependent proliferation. Utilizing deletion and mutagenesis approaches, we mapped the interaction of CAP1-cyclase with CAP’s N-terminal domain involving critical leucine residues in the conserved RLE motifs and adenylyl cyclase’s conserved catalytic loops (e.g., C1a and/or C2a). When combined with a FRET-based cAMP sensor, CAP1 overexpression–knockdown strategies, and the use of constitutively active and negative regulators of Rap1, our studies highlight a critical role for CAP1-Rap1 in adenylyl cyclase regulation in live cells. Similarly, we show that CAP1 modulation significantly affected cAMP-mediated proliferation in an RLE motif–dependent manner. The combined study indicates that CAP1-cyclase-Rap1 represents a regulatory unit in cAMP dynamics and biology. Since Rap1 is an established downstream effector of cAMP, we advance the hypothesis that CAP1-cyclase-Rap1 represents a positive feedback loop that might be involved in cAMP microdomain establishment and localized signaling.

scholarly journals The dendritic spatial code: branch-specific place tuning and its experience-dependent decoupling

2020 ◽  
Author(s):  
Shannon K. Rashid ◽  
Victor Pedrosa ◽  
Martial A. Dufour ◽  
Jason J. Moore ◽  
Spyridon Chavlis ◽  
...  
Keyword(s):  
Pyramidal Neurons ◽  
Pyramidal Cells ◽  
Dependent Manner ◽  
Single Plane ◽  
Two Photon Microscopy ◽  
Place Fields ◽  
Familiar Environment ◽  
Dendritic Branches ◽  
Hippocampal Pyramidal Cells

AbstractDendrites of pyramidal neurons integrate different sensory inputs, and non-linear dendritic computations drive feature selective tuning and plasticity. Yet little is known about how dendrites themselves represent the environment, the degree to which they are coupled to their soma, and how that coupling is sculpted with experience. In order to answer these questions, we developed a novel preparation in which we image soma and connected dendrites in a single plane across days using in vivo two-photon microscopy. Using this preparation, we monitored spatially tuned activity in area CA3 of the hippocampus in head-fixed mice running on a linear track. We identified “place dendrites”, which can stably and precisely represent both familiar and novel spatial environments. Dendrites could display place tuning independent of their connected soma and even their sister dendritic branches, the first evidence for branch-specific tuning in the hippocampus. In a familiar environment, spatially tuned somata were more decoupled from their dendrites as compared to non-tuned somata. This relationship was absent in a novel environment, suggesting an experience dependent selective gating of dendritic spatial inputs. We then built a data-driven multicompartment computational model that could capture the experimentally observed correlations. Our model predicts that place cells exhibiting branch-specific tuning have more flexible place fields, while neurons with homogenous or co-tuned dendritic branches have higher place field stability. These findings demonstrate that spatial representation is organized in a branch-specific manner within dendrites of hippocampal pyramidal cells. Further, spatial inputs from dendrites to soma are selectively and dynamically gated in an experience-dependent manner, endowing both flexibility and stability to the cognitive map of space.One sentence summaryHippocampal pyramidal cells show branch-specific tuning for different place fields, and their coupling to their soma changes with experience of an environment.

scholarly journals Carbon monoxide released by CORM-A1 prevents yeast cell death via autophagy stimulation

2019 ◽  
Vol 19 (5) ◽  
Author(s):  
Cláudia Figueiredo-Pereira ◽  
Regina Menezes ◽  
Sofia Ferreira ◽  
Cláudia N Santos ◽  
Helena L A Vieira
Keyword(s):  
Oxidative Stress ◽  
Carbon Monoxide ◽  
Cell Death ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Primary Cultures ◽  
Autophagic Flux ◽  
Dependent Manner ◽  
Yeast Saccharomyces Cerevisiae

ABSTRACT Autophagy is an autodigestive process, promoting cytoprotection by the elimination of dysfunctional organelles, misfolded proteins and toxic aggregates. Carbon monoxide (CO) is an endogenous gasotransmitter that under low concentrations prevents cell death and inflammation. For the first time, the role of autophagy in CO-mediated cytoprotection against oxidative stress was evaluated in the model yeast Saccharomyces cerevisiae. The boron-based CO-releasing molecule, CORM-A1, was used to deliver CO. CORM-A1 partially prevented oxidative stress-induced cell death in yeast. Likewise, CORM-A1 activated autophagy under basal physiological conditions, which were assessed by autophagic flux and the expression of mCherry-Atg8 or GFP-Atg8. Inhibition of autophagy by knocking out key autophagic genes in yeast (ATG8 or ATG11) blocked CORM-A1 cytoprotective effect, indicating the critical role of autophagy in CO-induced cytoprotection. The CO-mediated cytoprotection via autophagy induction observed in yeast was validated in primary cultures of astrocytes, a well-characterized model for CO's cytoprotective functions. As in yeast, CORM-A1 prevented oxidative stress-induced cell death in an autophagy-dependent manner in astrocytes. Overall, our data support the cytoprotective action of CO against oxidative stress. CO promotes cytoprotection in yeast via autophagy, opening new possibilities for the study of molecular mechanisms of CO's biological functions using this powerful eukaryotic model.

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