Aberrant astrocyte protein secretion contributes to altered neuronal development in diverse disorders

Astrocytes negatively impact neuronal development in a range of neurodevelopmental disorders (NDs), however how they do this, and if mechanisms are shared across multiple disorders, is not known. We developed an in vitro system to ask how astrocyte protein secretion and gene expression change in 3 genetic NDs. This identified disorder specific changes, as well as core proteins that are increased in release in all 3 NDs. ND astrocytes increase release of Igfbp2, and blocking Igfbp2 partially rescues the neurite outgrowth inhibitory effects of Rett Syndrome astrocytes. We identified that ND astrocytes upregulate release of Bmp6, which acts on astrocytes themselves and is upstream of astrocyte secretion changes in NDs. Blocking Bmp signaling in Fragile X Syndrome astrocytes reverses the inhibitory effects of FXS astrocytes on neuronal development. We provide a resource of astrocyte secreted proteins in health and NDs, as well as novel targets for intervention in diverse NDs.