Despite the importance of astrocytes in the CNS, how they become developmentally mature, especially the acquisition of their unique morphology and dynamic interaction with synapses/vasculatures and induction of astroglial functional genes, remains essentially unknown. We are interested in the molecular mechanisms of astrocytes’ functional maturation during postnatal development, especially the role of neuronal signals in astrocyte maturation. To answer these questions, we employ primary astrocyte and neuron co-cultures and in vivo mouse models in combination with molecular (TRAP-based mRNA profiling), imaging (in vivo astrocyte labeling and time-lapse imaging), genetic (Cre-loxP mouse/viral delivery), and electrophysiological (astrocyte patch and dye-filling) approaches. We have shown that neuronal glutamatergic signals play important roles in the functional maturation of astrocytes during postnatal development (J of Neuroscience, 2014). We have also characterized the regional and cortical-layer-dependent heterogeneity of astrocytes (J of Neuroscience, 2017; Glia, 2019). Recently, we identified and characterized a neuronal exosome-mediated miRNA pathway that regulates astroglial genetic functions (JBC, 2013; Nature Communications, 2019). We are actively investigating mechanisms involved in exosome-mediated neuron to glial communication.