Astrocytes, the largest glial population in human and murine brains, are crucial to the regulation of synaptic connectivity. During the first three weeks of postnatal development, immature astrocytes express mGlu5 and expands several fold while undergoing a transition towards their mature phase.
In astrocytes, the intracellular calcium (Ca2+) signaling mediated by activation of metabotropic glutamate receptor 5 (mGlu5) is crucially involved in the modulation of many aspects of brain physiology, including gliotransmission. Here, we find that the mGlu5-mediated Ca2+ signaling leading to release of glutamate is governed by mGlu5 interaction with Homer1 scaffolding proteins. We show that the long splice variants Homer1b/c are expressed in astrocytic processes, where they cluster with mGlu5 at sites displaying intense local Ca2+ activity.
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