Astroglial ER-mitochondria calcium transfer mediates endocannabinoid-dependent synaptic integration

Intracellular calcium signaling underlies the astroglial control of synaptic transmission and plasticity. Mitochondria-endoplasmic reticulum contacts (MERCs) are key determinants of calcium dynamics, but their functional impact on astroglial regulation of brain information processing is unexplored. We found that the activation of astrocyte mitochondrial-associated type-1 cannabinoid (mtCB1) receptors determines MERC-dependent intracellular calcium signaling and synaptic integration. The stimulation of mtCB1 receptors promotes calcium transfer from the endoplasmic reticulum to mitochondria through a specific molecular cascade, involving the mitochondrial calcium uniporter (MCU). Physiologically, mtCB1-dependent mitochondrial calcium uptake determines the dynamics of cytosolic calcium events in astrocytes upon endocannabinoid mobilization. Accordingly, electrophysiological recordings in hippocampal slices showed that conditional genetic exclusion of mtCB1 receptors or dominant-negative MCU expression in astrocytes blocks lateral synaptic potentiation, through which astrocytes integrate the activity of distant synapses. Altogether, these data reveal an endocannabinoid link between astroglial MERCs and the regulation of brain network functions. [Display omitted] •ER/mitochondria contacts in astrocytes are determinants of synaptic integration•Mitochondrial calcium uptake is actively modulated by mtCB1•Mitochondria-dependent calcium dynamics in astrocytes determine synaptic activity•Astroglial mtCB1 receptors are required for lateral synaptic plasticity Serrat et al. demonstrate that mitochondria-associated CB1 (mtCB1) receptors determine endocannabinoid-dependent intracellular calcium signaling in astrocytes to promote synaptic integration. Upon endocannabinoid mobilization, mtCB1 receptors favor calcium transfer from ER to mitochondria through a specific molecular cascade involving the mitochondrial calcium uniporter, thereby shaping the dynamics of cytosolic calcium events.