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Signaling at the gliovascular interface.
Marie Simard1, Gregory Arcuino, Takahiro Takano
1Department of Neurosurgery, New York Medical College, Valhalla, New York 10590, USA.
Summary
Astrocytes communicate via calcium signaling, particularly at the blood-brain barrier. This study reveals astrocytic end-feet express key proteins for purinergic signaling, influencing brain functions.
Area of Science:
- Neuroscience
- Cell Biology
- Neuroimmunology
Background:
- Astrocytes communicate via calcium signaling, modulating synaptic strength.
- This communication mechanism has not been fully integrated into astrocyte supportive functions.
- Astrocyte functions are closely linked to the blood-brain barrier (BBB).
Purpose of the Study:
- To investigate calcium signaling proteins in astrocyte vascular end-feet.
- To explore the role of astrocytic calcium signaling at the gliovascular interface.
- To understand astrocyte communication in relation to BBB functions.
Main Methods:
- Examined expression of gap junction protein Cx43 and purinergic receptors (P2Y2, P2Y4) in astrocyte end-feet.
- Utilized Lucifer yellow diffusion to trace glial end-foot connections.
- Employed multiphoton imaging with Fluo-4/AM to observe calcium dynamics in response to ATP and electrical stimulation.
Main Results:
- Cx43 was highly expressed around vessels, forming gap junctions between astrocytic end-feet.
- P2Y2 and P2Y4 receptors were localized at the gliovascular interface.
- ATP mobilized calcium in astrocytic end-feet; electrical stimulation induced calcium waves along vessel walls.
- Brain endothelial cells and pericytes showed weak responses to ATP.
Conclusions:
- Astrocytic end-feet at the vessel wall are identified as a hub for purinergic signaling.
- Calcium signaling in astrocytes may regulate BBB functions like blood flow, metabolism, and water homeostasis.
- This highlights a novel role for astrocyte-neuron communication at the neurovascular unit.