scholarly journals Astrocyte-Derived Small Extracellular Vesicles Regulate Dendritic Complexity through miR-26a-5p Activity

2020 ◽  
Author(s):  
Alejandro Luarte ◽  
Roberto Henzi ◽  
Anllely Fernández ◽  
Diego Gaete ◽  
Pablo Cisternas ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Hippocampal Neurons ◽  
Morphological Changes ◽  
Morphological Differentiation ◽  
Total Content ◽  
Neuronal Morphology ◽  
Cultured Astrocytes ◽  
Neuronal Proteins ◽  
Dendritic Complexity ◽  
Mirna Content

In the last decades, it has been established that astrocytes play key roles in the regulation of neuronal morphology. However, the contribution of astrocyte-derived small extracellular vesicles (sEVs) to morphological differentiation of neurons has only recently been addressed. Here, we showed that cultured astrocytes expressing a GFP tagged version of the stress-regulated astrocytic enzyme Aldolase C (Aldo C-GFP) release small extracellular vesicles (sEVs) which are transferred into cultured hippocampal neurons. Surprisingly, Aldo C-GFP-containing sEVs (Aldo C-GFP sEVs) displayed an exacerbated capacity to reduce the dendritic complexity in developing hippocampal neurons compared to sEVs derived from control (i.e. GFP-expressing) astrocytes. Using bioinformatics and biochemical tools, we found that the total content of overexpressed Aldo C-GFP correlates with an increased content of endogenous miRNA-26a-5p in both total astrocyte homogenates and sEVs. Notably, neurons magnetofected with a nucleotide sequence that mimics endogenous miRNA-26a-5p (mimic 26a-5p) not only decreased the levels of neuronal proteins associated to morphogenesis regulation and also reproduced morphological changes induced by Aldo-C-GFP sEVs. Furthermore, neurons magnetofected with a sequence targeting miRNA-26a-5p (antago 26a-5p) were largely resistant to Aldo C-GFP sEVs. Our results support a novel and complex level of astrocyte-to-neuron communication mediated by astrocyte-derived sEVs and the activity of their miRNA content.

scholarly journals Astrocyte-Derived Small Extracellular Vesicles Regulate Dendritic Complexity through miR-26a-5p Activity

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 930 ◽  
Author(s):  
Alejandro Luarte ◽  
Roberto Henzi ◽  
Anllely Fernández ◽  
Diego Gaete ◽  
Pablo Cisternas ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Hippocampal Neurons ◽  
Morphological Changes ◽  
Morphological Differentiation ◽  
Total Content ◽  
Neuronal Morphology ◽  
Cultured Astrocytes ◽  
Neuronal Proteins ◽  
Dendritic Complexity ◽  
Mirna Content

In the last few decades, it has been established that astrocytes play key roles in the regulation of neuronal morphology. However, the contribution of astrocyte-derived small extracellular vesicles (sEVs) to morphological differentiation of neurons has only recently been addressed. Here, we showed that cultured astrocytes expressing a GFP-tagged version of the stress-regulated astrocytic enzyme Aldolase C (Aldo C-GFP) release small extracellular vesicles (sEVs) that are transferred into cultured hippocampal neurons. Surprisingly, Aldo C-GFP-containing sEVs (Aldo C-GFP sEVs) displayed an exacerbated capacity to reduce the dendritic complexity in developing hippocampal neurons compared to sEVs derived from control (i.e., GFP-expressing) astrocytes. Using bioinformatics and biochemical tools, we found that the total content of overexpressed Aldo C-GFP correlates with an increased content of endogenous miRNA-26a-5p in both total astrocyte homogenates and sEVs. Notably, neurons magnetofected with a nucleotide sequence that mimics endogenous miRNA-26a-5p (mimic 26a-5p) not only decreased the levels of neuronal proteins associated to morphogenesis regulation, but also reproduced morphological changes induced by Aldo-C-GFP sEVs. Furthermore, neurons magnetofected with a sequence targeting miRNA-26a-5p (antago 26a-5p) were largely resistant to Aldo C-GFP sEVs. Our results support a novel and complex level of astrocyte-to-neuron communication mediated by astrocyte-derived sEVs and the activity of their miRNA content.

scholarly journals Tail-vein injection of MSC-derived small extracellular vesicles facilitates the restoration of hippocampal neuronal morphology and function in APP / PS1 mice

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Han Wang ◽  
Yuqi Liu ◽  
Junchen Li ◽  
Tian Wang ◽  
Yue Hei ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Extracellular Vesicles ◽  
Hippocampal Neurons ◽  
Calcium Oscillations ◽  
Neuronal Morphology ◽  
Great Promise ◽  
Related Factor ◽  
In Vivo Models ◽  
Nrf2 Signaling Pathway ◽  
And Function

AbstractMesenchymal stem-cell-derived small extracellular vesicles (MSC-EVs), as a therapeutic agent, have shown great promise in the treatment of neurological diseases. To date, the neurorestorative effects and underlying mechanism of MSC-EVs in Alzheimer’s disease (AD) are not well known. Herein, we aimed to investigate the action of MSC-EVs on the neuronal deficits in β-amyloid protein (Aβ)-stimulated hippocampal neurons, or AD cell (SHSY5Y cell lines) and animal (APPswe / PS1dE9 mice) models. In the present study, the cell and AD models received a single-dose of MSC-EVs, and were then assessed for behavioral deficits, pathological changes, intracellular calcium transients, neuronal morphology alterations, or electrophysiological variations. Additionally, the nuclear factor E2-related factor 2 (Nrf2, a key mediator of neuronal injury in AD) signaling pathway was probed by western blotting in vitro and in vivo models of AD. Our results showed that MSC-EVs therapy improved the cognitive impairments and reduced the hippocampal Aβ aggregation and neuronal loss in AD mice. Markedly, EV treatment restored the calcium oscillations, dendritic spine alterations, action potential abnormalities, or mitochondrial changes in the hippocampus of AD models. Also, we found that the Nrf2 signaling pathway participated in the actions of MSC-EVs in the cell and animal models. Together, these data indicate that MS-EVs as promising nanotherapeutics for restoration of hippocampal neuronal morphology and function in APP / PS1 mice, further highlighting the clinical values of MSC-EVs in the treatment of AD.

scholarly journals Dendritic complexity change in the triple transgenic mouse model of Alzheimer’s disease

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8178
Author(s):  
Yu Zhang ◽  
Zhenlong Xiao ◽  
Zhijun He ◽  
Junyu Chen ◽  
Xin Wang ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
High Resolution ◽  
Primary Motor Cortex ◽  
Morphological Changes ◽  
Executive Dysfunction ◽  
Neuronal Morphology ◽  
Model Of Alzheimer’S Disease ◽  
Dendritic Complexity ◽  
Old Mice

Alzheimer’s disease (AD) is an irreversible, neurodegenerative disease that is characterized by memory impairment and executive dysfunction. However, the change of fine structure of neuronal morphology remains unclear in the AD model mouse. In this study, high-resolution mouse brain sectional images were scanned by Micro-Optical Sectioning Tomography (MOST) technology and reconstructed three-dimensionally to obtain the pyramidal neurons. The method of Sholl analysis was performed to analyze the neurons in the brains of 6- and 12-month-old AD mice. The results showed that dendritic complexity was not affected in the entorhinal cortex between 6-month-old mice and 12-month-old mice. The dendritic complexity had increased in the primary motor cortex and CA1 region of hippocampus of 12- month-old mice compared with 6-month-old mice. On the contrary, dendritic complexity in the prefrontal cortex was decreased significantly between 6-month-old and 12-month-old mice. To our knowledge, this is the first study to provide high-resolution brain images of triple transgenic AD mice for statistically analyzing neuronal dendrite complexity by MOST technology to reveal the morphological changes of neurons during AD progression.

scholarly journals Extracellular Vesicles Analysis in the COVID-19 Era: Insights on Serum Inactivation Protocols towards Downstream Isolation and Analysis

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 544
Author(s):  
Roberto Frigerio ◽  
Angelo Musicò ◽  
Marco Brucale ◽  
Andrea Ridolfi ◽  
Silvia Galbiati ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Analytical Techniques ◽  
Heat Inactivation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Droplet Pcr ◽  
Detergent Treatment ◽  
Routine Procedures ◽  
The Impact ◽  
Mirna Content

Since the outbreak of the COVID-19 crisis, the handling of biological samples from confirmed or suspected SARS-CoV-2-positive individuals demanded the use of inactivation protocols to ensure laboratory operators’ safety. While not standardized, these practices can be roughly divided into two categories, namely heat inactivation and solvent-detergent treatments. These routine procedures should also apply to samples intended for Extracellular Vesicles (EVs) analysis. Assessing the impact of virus-inactivating pre-treatments is therefore of pivotal importance, given the well-known variability introduced by different pre-analytical steps on downstream EVs isolation and analysis. Arguably, shared guidelines on inactivation protocols tailored to best address EVs-specific requirements will be needed among the analytical community, yet deep investigations in this direction have not yet been reported. We here provide insights into SARS-CoV-2 inactivation practices to be adopted prior to serum EVs analysis by comparing solvent/detergent treatment vs. heat inactivation. Our analysis entails the evaluation of EVs recovery and purity along with biochemical, biophysical and biomolecular profiling by means of a set of complementary analytical techniques: Nanoparticle Tracking Analysis, Western Blotting, Atomic Force Microscopy, miRNA content (digital droplet PCR) and tetraspanin assessment by microarrays. Our data suggest an increase in ultracentrifugation (UC) recovery following heat treatment; however, it is accompanied by a marked enrichment in EVs-associated contaminants. On the other hand, solvent/detergent treatment is promising for small EVs (<150 nm range), yet a depletion of larger vesicular entities was detected. This work represents a first step towards the identification of optimal serum inactivation protocols targeted to EVs analysis.

scholarly journals RhoA/ROCK regulation of neuritogenesis via profilin IIa–mediated control of actin stability

2003 ◽  
Vol 162 (7) ◽  
pp. 1267-1279 ◽  
Author(s):  
Jorge Santos Da Silva ◽  
Miguel Medina ◽  
Cecilia Zuliani ◽  
Alessia Di Nardo ◽  
Walter Witke ◽  
...  
Keyword(s):  
Neuronal Differentiation ◽  
Hippocampal Neurons ◽  
Morphological Changes ◽  
Decisive Role ◽  
Central Mechanism ◽  
Actin Binding ◽  
Actin Binding Protein ◽  
Rhoa Activity ◽  
Neuronal Soma ◽  
Cultured Hippocampal Neurons

Neuritogenesis, the first step of neuronal differentiation, takes place as nascent neurites bud from the immediate postmitotic neuronal soma. Little is known about the mechanisms underlying the dramatic morphological changes that characterize this event. Here, we show that RhoA activity plays a decisive role during neuritogenesis of cultured hippocampal neurons by recruiting and activating its specific kinase ROCK, which, in turn, complexes with profilin IIa. We establish that this previously uncharacterized brain-specific actin-binding protein controls neurite sprouting by modifying actin stability, a function regulated by ROCK-mediated phosphorylation. Furthermore, we determine that this novel cascade is switched on or off by physiological stimuli. We propose that RhoA/ROCK/PIIa-mediated regulation of actin stability, shown to be essential for neuritogenesis, may constitute a central mechanism throughout neuronal differentiation.

scholarly journals A Peptidoglycan-Remodeling Enzyme Is Critical for Bacteroid Differentiation in Bradyrhizobium spp. During Legume Symbiosis

2016 ◽  
Vol 29 (6) ◽  
pp. 447-457 ◽  
Author(s):  
Djamel Gully ◽  
Daniel Gargani ◽  
Katia Bonaldi ◽  
Cédric Grangeteau ◽  
Clémence Chaintreuil ◽  
...  
Keyword(s):  
Immune Responses ◽  
Essential Role ◽  
Morphological Changes ◽  
Large Fraction ◽  
Morphological Differentiation ◽  
Capsular Polysaccharides ◽  
Cell Enlargement ◽  
Legume Symbiosis ◽  
Bradyrhizobium Spp ◽  
Peptidoglycan Layer

In response to the presence of compatible rhizobium bacteria, legumes form symbiotic organs called nodules on their roots. These nodules house nitrogen-fixing bacteroids that are a differentiated form of the rhizobium bacteria. In some legumes, the bacteroid differentiation comprises a dramatic cell enlargement, polyploidization, and other morphological changes. Here, we demonstrate that a peptidoglycan-modifying enzyme in Bradyrhizobium strains, a DD-carboxypeptidase that contains a peptidoglycan-binding SPOR domain, is essential for normal bacteroid differentiation in Aeschynomene species. The corresponding mutants formed bacteroids that are malformed and hypertrophied. However, in soybean, a plant that does not induce morphological differentiation of its symbiont, the mutation does not affect the bacteroids. Remarkably, the mutation also leads to necrosis in a large fraction of the Aeschynomene nodules, indicating that a normally formed peptidoglycan layer is essential for avoiding the induction of plant immune responses by the invading bacteria. In addition to exopolysaccharides, capsular polysaccharides, and lipopolysaccharides, whose role during symbiosis is well defined, our work demonstrates an essential role in symbiosis for yet another rhizobial envelope component, the peptidoglycan layer.

scholarly journals Mathematical Model of Neuronal Morphology: Prenatal Development of the Human Dentate Nucleus

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Katarina Rajković ◽  
Goran Bačić ◽  
Dušan Ristanović ◽  
Nebojša T. Milošević
Keyword(s):  
Mathematical Model ◽  
Dentate Nucleus ◽  
Morphological Changes ◽  
Prenatal Development ◽  
Morphometric Parameters ◽  
Neuronal Morphology ◽  
Dendritic Arbor ◽  
Complex Development ◽  
Sound Foundation ◽  
The Mathematical Model

The aim of the study was to quantify the morphological changes of the human dentate nucleus during prenatal development using mathematical models that take into account main morphometric parameters. The camera lucida drawings of Golgi impregnated neurons taken from human fetuses of gestational ages ranging from 14 to 41 weeks were analyzed. Four morphometric parameters, the size of the neuron, the dendritic complexity, maximum dendritic density, and the position of maximum density, were obtained using the modified Scholl method and fractal analysis. Their increase during the entire prenatal development can be adequately fitted with a simple exponential. The three parameters describing the evolution of branching complexity of the dendritic arbor positively correlated with the increase of the size of neurons, but with different rate constants, showing that the complex development of the dendritic arbor is complete during the prenatal period. The findings of the present study are in accordance with previous crude qualitative data on prenatal development of the human dentate nucleus, but provide much greater amount of fine details. The mathematical model developed here provides a sound foundation enabling further studies on natal development or analyzing neurological disorders during prenatal development.

Initiation and maintenance of NGF-stimulated neurite outgrowth requires activation of a phosphoinositide 3-kinase

1996 ◽  
Vol 109 (2) ◽  
pp. 289-300 ◽  
Author(s):  
T.R. Jackson ◽  
I.J. Blader ◽  
L.P. Hammonds-Odie ◽  
C.R. Burga ◽  
F. Cooke ◽  
...  
Keyword(s):  
Neurite Outgrowth ◽  
Pc12 Cells ◽  
Specific Inhibitor ◽  
Morphological Differentiation ◽  
Sympathetic Neuron ◽  
Neuronal Morphology ◽  
Regulatory Subunit ◽  
Membrane Reorganization ◽  
Phosphoinositide 3 Kinase

Application of nerve growth factor (NGF) to PC12 cells stimulates a programme of physiological changes leading to the development of a sympathetic neuron like phenotype, one aspect of which is the development of a neuronal morphology characterised by the outgrowth of neuritic processes. We have investigated the role of phosphoinositide 3-kinase in NGF-stimulated morphological differentiation through two approaches: firstly, preincubation with wortmannin, a reputedly specific inhibitor of phosphoinositide kinases, completely inhibited initial morphological responses to NGF, the formation of actin filament rich microspikes and subsequent neurite outgrowth. This correlated with wortmannin inhibition of NGF-stimulated phosphatidylinositol(3,4,5)trisphosphate (PtdInsP3) and phosphatidylinositol(3,4)bisphosphate (PtdIns(3,4)P2) production and with inhibition of NGF-stimulated phosphoinositide 3-kinase activity in anti-phosphotyrosine immunoprecipitates. Secondly, the overexpression of a mutant p85 regulatory subunit of the phosphoinositide 3-kinase, which cannot interact with the catalytic p110 subunit, also substantially inhibited the initiation of NGF-stimulated neurite outgrowth. In addition, we found that wortmannin caused a rapid collapse of more mature neurites formed following several days exposure of PC12 cells to NGF. These results indicate that NGF-stimulated neurite outgrowth requires the activity of a tyrosine kinase regulated PI3-kinase and suggest that the primary product of this enzyme, PtdInsP3, is a necessary second messenger for the cytoskeletal and membrane reorganization events which occur during neuronal differentiation.

Methionine and methionine sulfoxide induces neurochemical and morphological changes in cultured astrocytes: Involvement of Na+, K+-ATPase activity, oxidative status, and cholinergic and purinergic signaling

2020 ◽  
Vol 77 ◽  
pp. 60-70 ◽  
Author(s):  
Mayara Sandrielly Pereira Soares ◽  
Nathalia Stark Pedra ◽  
Natália Pontes Bona ◽  
Anita Ávila de Souza ◽  
Fernanda Cardoso Teixeira ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Morphological Changes ◽  
Purinergic Signaling ◽  
Methionine Sulfoxide ◽  
Oxidative Status ◽  
Cultured Astrocytes

scholarly journals Effect of Methionine Diet on Time-Related Metabolic and Histopathological Changes of Rat Hippocampus in the Model of Global Brain Ischemia

Biomolecules ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1128
Author(s):  
Maria Kovalska ◽  
Petra Hnilicova ◽  
Dagmar Kalenska ◽  
Anna Tomascova ◽  
Marian Adamkov ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Hippocampal Neurons ◽  
Morphological Changes ◽  
Ischemia Reperfusion ◽  
Immunohistochemical Analysis ◽  
Selective Vulnerability ◽  
Rat Hippocampus ◽  
Resonance Spectroscopy ◽  
Vessel Occlusion ◽  
Global Brain Ischemia

Hyperhomocysteinemia (hHcy) represents a strong risk factor for atherosclerosis-associated diseases, like stroke, dementia or Alzheimer’s disease. A methionine (Met)-rich diet leads to an elevated level of homocysteine in plasma and might cause pathological alterations across the brain. The hippocampus is being constantly studied for its selective vulnerability linked with neurodegeneration. This study explores metabolic and histo-morphological changes in the rat hippocampus after global ischemia in the hHcy conditions using a combination of proton magnetic resonance spectroscopy and magnetic resonance-volumetry as well as immunohistochemical analysis. After 4 weeks of a Met-enriched diet at a dose of 2 g/kg of animal weight/day, adult male Wistar rats underwent 4-vessel occlusion lasting for 15 min, followed by a reperfusion period varying from 3 to 7 days. Histo-morphological analyses showed that the subsequent ischemia-reperfusion insult (IRI) aggravates the extent of the sole hHcy-induced degeneration of the hippocampal neurons. Decreased volume in the grey matter, extensive changes in the metabolic ratio, deeper alterations in the number and morphology of neurons, astrocytes and their processes were demonstrated in the hippocampus 7 days post-ischemia in the hHcy animals. Our results suggest that the combination of the two risk factors (hHcy and IRI) endorses and exacerbates the rat hippocampal neurodegenerative processes.

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