Membrane Associated RNA‐Containing Vesicles Regulate Cortical Astrocytic Microdomain Calcium Transients in Awake Ischemic Stroke Mice

Abstract Astrocytic processes minutely regulate neuronal activity via tripartite synaptic structures. The precision‐tuning of the function of astrocytic processes is garnering increasing attention because of its significance in promoting brain repair following ischemic stroke. Microdomain calcium (Ca 2+ ) transients in astrocytic processes are pivotal for the functional regulation of these processes. However, the understanding of the alterations and regulatory mechanism of microdomain Ca 2+ transients during stroke remains limited. In the present study, a fast high‐resolution, miniaturized two‐photon microscopy is used to show that the levels of astrocytic microdomain Ca 2+ transients are significantly reduced in the peri‐infarct area of awake ischemic stroke mice. This finding correlated with the behavioral deficits shown by these mice under freely‐moving conditions. Mitochondrial Ca 2+ activity is an important factor driving the microdomain Ca 2+ transients. DEAD Box 1 (DDX1) bound to circSCMH1 (a circular RNA involved in vascular post‐stroke repair) facilitates the formation of membrane‐associated RNA‐containing vesicles (MARVs) and enhances the activity of astrocytic microdomain Ca 2+ transients, thereby promoting behavioral recovery. These results show that targeting astrocytic microdomain Ca 2+ transients is a potential therapeutic approach in stroke intervention.