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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

Neuronal exosomes bearing GFP–TTC preferentially bind to pre-synaptic terminals and can be internalized. Exosomes secreted by cortical neurons preincubated with GFP–TTC (green) were incubated for 1 h on hippocampal neurons (22 DIV), which were then immunostained with (A) anti-synaptophysin (magenta) or (B) anti-PSD95 (magenta). Confocal microscopy sections show patches of GFP–TTC exosomes (green) perfectly colocalized with some synaptophysin-positive presynaptic sites and juxtaposed with some PSD95-positive post-synaptic sites. Scale bars: (A, B, C) 10 µm. (C) GFP–TTC exosomes were incubated for 1 h on hippocampal neurons (21 DIV) preincubated with Alexa594-WGA for 10 min at 37°C to label endosomes. (A), (B) (C) are confocal sections except for the photo on the right of the (C) panel, representing the projection of maximal intensities. Thin and bold arrows show labelling on the surface and within the cytoplasm respectively.
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Figure 0005: Neuronal exosomes bearing GFP–TTC preferentially bind to pre-synaptic terminals and can be internalized. Exosomes secreted by cortical neurons preincubated with GFP–TTC (green) were incubated for 1 h on hippocampal neurons (22 DIV), which were then immunostained with (A) anti-synaptophysin (magenta) or (B) anti-PSD95 (magenta). Confocal microscopy sections show patches of GFP–TTC exosomes (green) perfectly colocalized with some synaptophysin-positive presynaptic sites and juxtaposed with some PSD95-positive post-synaptic sites. Scale bars: (A, B, C) 10 µm. (C) GFP–TTC exosomes were incubated for 1 h on hippocampal neurons (21 DIV) preincubated with Alexa594-WGA for 10 min at 37°C to label endosomes. (A), (B) (C) are confocal sections except for the photo on the right of the (C) panel, representing the projection of maximal intensities. Thin and bold arrows show labelling on the surface and within the cytoplasm respectively.

Mentions: GFP–TTC exosomes bound to neurons are often concentrated in patches, reminiscent of synapses. Immuno-labelling of neurons decorated by GFP–TTC-exosomes with antibodies against synaptophysin and PSD95 was used to label pre- and post-synaptic sites, respectively. As illustrated in Fig. 5, some fluorescent patches corresponding to GFP–TTC exosomes co-localized with synaptophysin (Fig. 5A) and juxtaposed with PSD95 (Fig. 5B), demonstrating that neuronal exosomes bind to pre-synaptic parts. Noteworthy is that GFP–TTC-exosomes bound only to a small fraction of the immunolabelled synapses.


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)

Neuronal exosomes bearing GFP–TTC preferentially bind to pre-synaptic terminals and can be internalized. Exosomes secreted by cortical neurons preincubated with GFP–TTC (green) were incubated for 1 h on hippocampal neurons (22 DIV), which were then immunostained with (A) anti-synaptophysin (magenta) or (B) anti-PSD95 (magenta). Confocal microscopy sections show patches of GFP–TTC exosomes (green) perfectly colocalized with some synaptophysin-positive presynaptic sites and juxtaposed with some PSD95-positive post-synaptic sites. Scale bars: (A, B, C) 10 µm. (C) GFP–TTC exosomes were incubated for 1 h on hippocampal neurons (21 DIV) preincubated with Alexa594-WGA for 10 min at 37°C to label endosomes. (A), (B) (C) are confocal sections except for the photo on the right of the (C) panel, representing the projection of maximal intensities. Thin and bold arrows show labelling on the surface and within the cytoplasm respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 0005: Neuronal exosomes bearing GFP–TTC preferentially bind to pre-synaptic terminals and can be internalized. Exosomes secreted by cortical neurons preincubated with GFP–TTC (green) were incubated for 1 h on hippocampal neurons (22 DIV), which were then immunostained with (A) anti-synaptophysin (magenta) or (B) anti-PSD95 (magenta). Confocal microscopy sections show patches of GFP–TTC exosomes (green) perfectly colocalized with some synaptophysin-positive presynaptic sites and juxtaposed with some PSD95-positive post-synaptic sites. Scale bars: (A, B, C) 10 µm. (C) GFP–TTC exosomes were incubated for 1 h on hippocampal neurons (21 DIV) preincubated with Alexa594-WGA for 10 min at 37°C to label endosomes. (A), (B) (C) are confocal sections except for the photo on the right of the (C) panel, representing the projection of maximal intensities. Thin and bold arrows show labelling on the surface and within the cytoplasm respectively.
Mentions: GFP–TTC exosomes bound to neurons are often concentrated in patches, reminiscent of synapses. Immuno-labelling of neurons decorated by GFP–TTC-exosomes with antibodies against synaptophysin and PSD95 was used to label pre- and post-synaptic sites, respectively. As illustrated in Fig. 5, some fluorescent patches corresponding to GFP–TTC exosomes co-localized with synaptophysin (Fig. 5A) and juxtaposed with PSD95 (Fig. 5B), demonstrating that neuronal exosomes bind to pre-synaptic parts. Noteworthy is that GFP–TTC-exosomes bound only to a small fraction of the immunolabelled synapses.

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