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Exosomes secreted by cortical neurons upon glutamatergic synapse activation specifically interact with neurons.

Chivet M, Javalet C, Laulagnier K, Blot B, Hemming FJ, Sadoul R - J Extracell Vesicles (2014)

Bottom Line: We found that exosomes from neuroblastoma cells bind indiscriminately to neurons and glial cells and could be endocytosed preferentially by glial cells.In contrast, exosomes secreted from stimulated cortical neurons bound to and were endocytosed only by neurons.Thus, our results demonstrate for the first time that exosomes released upon synaptic activation do not bind to glial cells but selectively to other neurons suggesting that they can underlie a novel aspect of interneuronal communication.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM), U836, Grenoble, France; Grenoble Institute of Neuroscience, University of Grenoble Alpes, Grenoble, France.

ABSTRACT
Exosomes are nano-sized vesicles of endocytic origin released into the extracellular space upon fusion of multivesicular bodies with the plasma membrane. Exosomes represent a novel mechanism of cell-cell communication allowing direct transfer of proteins, lipids and RNAs. In the nervous system, both glial and neuronal cells secrete exosomes in a way regulated by glutamate. It has been hypothesized that exosomes can be used for interneuronal communication implying that neuronal exosomes should bind to other neurons with some kind of specificity. Here, dissociated hippocampal cells were used to compare the specificity of binding of exosomes secreted by neuroblastoma cells to that of exosomes secreted by cortical neurons. We found that exosomes from neuroblastoma cells bind indiscriminately to neurons and glial cells and could be endocytosed preferentially by glial cells. In contrast, exosomes secreted from stimulated cortical neurons bound to and were endocytosed only by neurons. Thus, our results demonstrate for the first time that exosomes released upon synaptic activation do not bind to glial cells but selectively to other neurons suggesting that they can underlie a novel aspect of interneuronal communication.

No MeSH data available.


Related in: MedlinePlus

GFP–TTC exosomes do not bind to the neuronal surface because of their TTC cargo. (A, B) Incubation with TTC abolishes GFP–TTC staining of neurons: GFP–TTC was diluted to 0.36 nM in culture medium and incubated for 1 h on 16 DIV hippocampal neurons in absence (A) or in presence (B) of 100 nM TTC. In B) cells were pre-incubated for 20 min with 100 nM TTC. (C, D) TTC does not impair binding of GFP–TTC-exosomes to neurons: GFP–TTC-exosomes were incubated for 1 h on 16 DIV hippocampal neurons in absence (C) or in presence (D) of 100 nM TTC. In D) cells were pre-incubated for 20 min with 100 nM TTC. After incubation, cells were washed, fixed and immunolabelled with anti-MAP2 (red) (A, B, C and D). Scale bars: 10 µm.
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Figure 0006: GFP–TTC exosomes do not bind to the neuronal surface because of their TTC cargo. (A, B) Incubation with TTC abolishes GFP–TTC staining of neurons: GFP–TTC was diluted to 0.36 nM in culture medium and incubated for 1 h on 16 DIV hippocampal neurons in absence (A) or in presence (B) of 100 nM TTC. In B) cells were pre-incubated for 20 min with 100 nM TTC. (C, D) TTC does not impair binding of GFP–TTC-exosomes to neurons: GFP–TTC-exosomes were incubated for 1 h on 16 DIV hippocampal neurons in absence (C) or in presence (D) of 100 nM TTC. In D) cells were pre-incubated for 20 min with 100 nM TTC. After incubation, cells were washed, fixed and immunolabelled with anti-MAP2 (red) (A, B, C and D). Scale bars: 10 µm.

Mentions: With GFP–TTC being on the surface of neuronal exosomes, it was conceivable that it might mediate the binding of exosomes to TTC receptors of the neuronal surface. In order to test whether this is the case, we used unlabelled purified TTC to compete for the binding of GFP–TTC-exosomes. As seen in Fig. 6, purified TTC abolished the binding of soluble GFP–TTC to hippocampal neurons (Fig. 6A and B), whereas it had no apparent effect on the binding of GFP–TTC exosomes (Fig. 6C and D). This result confirmed that the fluorescence detected on the surface of neurons incubated with GFP–TTC-exosomes is not due to soluble GFP–TTC and that GFP–TTC present on the exosomes does not mediate binding of the exosomes to the surface of hippocampal neurons.


Exosomes secreted by cortical neurons upon glutamatergic synapse activation specifically interact with neurons.

Chivet M, Javalet C, Laulagnier K, Blot B, Hemming FJ, Sadoul R - J Extracell Vesicles (2014)

GFP–TTC exosomes do not bind to the neuronal surface because of their TTC cargo. (A, B) Incubation with TTC abolishes GFP–TTC staining of neurons: GFP–TTC was diluted to 0.36 nM in culture medium and incubated for 1 h on 16 DIV hippocampal neurons in absence (A) or in presence (B) of 100 nM TTC. In B) cells were pre-incubated for 20 min with 100 nM TTC. (C, D) TTC does not impair binding of GFP–TTC-exosomes to neurons: GFP–TTC-exosomes were incubated for 1 h on 16 DIV hippocampal neurons in absence (C) or in presence (D) of 100 nM TTC. In D) cells were pre-incubated for 20 min with 100 nM TTC. After incubation, cells were washed, fixed and immunolabelled with anti-MAP2 (red) (A, B, C and D). Scale bars: 10 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4232649&req=5

Figure 0006: GFP–TTC exosomes do not bind to the neuronal surface because of their TTC cargo. (A, B) Incubation with TTC abolishes GFP–TTC staining of neurons: GFP–TTC was diluted to 0.36 nM in culture medium and incubated for 1 h on 16 DIV hippocampal neurons in absence (A) or in presence (B) of 100 nM TTC. In B) cells were pre-incubated for 20 min with 100 nM TTC. (C, D) TTC does not impair binding of GFP–TTC-exosomes to neurons: GFP–TTC-exosomes were incubated for 1 h on 16 DIV hippocampal neurons in absence (C) or in presence (D) of 100 nM TTC. In D) cells were pre-incubated for 20 min with 100 nM TTC. After incubation, cells were washed, fixed and immunolabelled with anti-MAP2 (red) (A, B, C and D). Scale bars: 10 µm.
Mentions: With GFP–TTC being on the surface of neuronal exosomes, it was conceivable that it might mediate the binding of exosomes to TTC receptors of the neuronal surface. In order to test whether this is the case, we used unlabelled purified TTC to compete for the binding of GFP–TTC-exosomes. As seen in Fig. 6, purified TTC abolished the binding of soluble GFP–TTC to hippocampal neurons (Fig. 6A and B), whereas it had no apparent effect on the binding of GFP–TTC exosomes (Fig. 6C and D). This result confirmed that the fluorescence detected on the surface of neurons incubated with GFP–TTC-exosomes is not due to soluble GFP–TTC and that GFP–TTC present on the exosomes does not mediate binding of the exosomes to the surface of hippocampal neurons.

Bottom Line: We found that exosomes from neuroblastoma cells bind indiscriminately to neurons and glial cells and could be endocytosed preferentially by glial cells.In contrast, exosomes secreted from stimulated cortical neurons bound to and were endocytosed only by neurons.Thus, our results demonstrate for the first time that exosomes released upon synaptic activation do not bind to glial cells but selectively to other neurons suggesting that they can underlie a novel aspect of interneuronal communication.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM), U836, Grenoble, France; Grenoble Institute of Neuroscience, University of Grenoble Alpes, Grenoble, France.

ABSTRACT
Exosomes are nano-sized vesicles of endocytic origin released into the extracellular space upon fusion of multivesicular bodies with the plasma membrane. Exosomes represent a novel mechanism of cell-cell communication allowing direct transfer of proteins, lipids and RNAs. In the nervous system, both glial and neuronal cells secrete exosomes in a way regulated by glutamate. It has been hypothesized that exosomes can be used for interneuronal communication implying that neuronal exosomes should bind to other neurons with some kind of specificity. Here, dissociated hippocampal cells were used to compare the specificity of binding of exosomes secreted by neuroblastoma cells to that of exosomes secreted by cortical neurons. We found that exosomes from neuroblastoma cells bind indiscriminately to neurons and glial cells and could be endocytosed preferentially by glial cells. In contrast, exosomes secreted from stimulated cortical neurons bound to and were endocytosed only by neurons. Thus, our results demonstrate for the first time that exosomes released upon synaptic activation do not bind to glial cells but selectively to other neurons suggesting that they can underlie a novel aspect of interneuronal communication.

No MeSH data available.


Related in: MedlinePlus