Primary cilia shape postnatal astrocyte development through Sonic hedgehog signaling

Primary cilia function as specialized signaling centers that regulate many cellular processes including neuron and glial development. Astrocytes possess cilia, but the function of cilia in astrocyte development remains largely unexplored. Here, we show that a sub-population of developing astrocytes in the prefrontal cortex are ciliated. Genetic ablation of astrocyte cilia in vivo at two distinct stages of astrocyte development results in altered Sonic hedgehog signaling. We show that Shh activity is decreased in immature and mature astrocytes upon loss of cilia. This connects astrocyte cilia and Shh signaling throughout the development of the astrocyte lineage. Furthermore, loss of cilia in immature astrocytes results in decreased astrocyte proliferation and loss of cilia in mature astrocytes causes enlarged astrocyte morphology. Together, these results indicates that astrocytes require cilia for Shh signaling and reveals that cilia function in astrocyte proliferation and morphological development.