Astrocytes extensively infiltrate the neuropil to regulate critical aspects of synaptic development and function. This process is regulated by transcellular interactions between astrocytes and neurons via cell adhesion molecules. How astrocytes coordinate developmental processes among one another to parse out the synaptic neuropil and form non-overlapping territories is unknown. Here we identify a molecular mechanism regulating astrocyte-astrocyte interactions during development to coordinate astrocyte morphogenesis and gap junction coupling. We show that hepaCAM, a disease-linked, astrocyte-enriched cell adhesion molecule, regulates astrocyte competition for territory and morphological complexity in the developing mouse cortex. Furthermore, conditional deletion of Hepacam from developing astrocytes significantly impairs gap junction coupling between astrocytes and disrupts the balance between synaptic excitation and inhibition. Mutations in HEPACAM cause megalencephalic leukoencephalopathy with subcortical cysts in humans. Therefore, our findings suggest that disruption of astrocyte self-organization mechanisms could be an underlying cause of neural pathology.
This work was supported by the National Institutes of Health (R01 DA047258 and R01 NS102237 to C.E., F32 NS100392 to K.T.B.) and the Holland-Trice Brain Research Award (to C.E.). K.T.B. was supported by postdoctoral fellowships from the Foerster-Bernstein Family and The Hartwell Foundation. The Hippenmeyer lab was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovations program (725780 LinPro) to S.H. R.E. was supported by Ministerio de Ciencia y Tecnología (RTI2018-093493-B-I00). We thank the Duke Light Microscopy Core Facility, the Duke Transgenic Mouse Facility, Dr. U. Schulte for assistance with proteomic experiments, and Dr. D. Silver for critical review of the manuscript. Cartoon elements of figure panels were created using BioRender.com.
Baldwin KT, Tan CX, Strader ST, et al. HepaCAM controls astrocyte self-organization and coupling. Neuron. 2021;109(15):2427-2442.e10. doi:10.1016/j.neuron.2021.05.025
Baldwin, K. T., Tan, C. X., Strader, S. T., Jiang, C., Savage, J. T., Elorza-Vidal, X., … Eroglu, C. (2021). HepaCAM controls astrocyte self-organization and coupling. Neuron. Elsevier. https://doi.org/10.1016/j.neuron.2021.05.025
Baldwin, Katherine T., Christabel X. Tan, Samuel T. Strader, Changyu Jiang, Justin T. Savage, Xabier Elorza-Vidal, Ximena Contreras, et al. “HepaCAM Controls Astrocyte Self-Organization and Coupling.” Neuron. Elsevier, 2021. https://doi.org/10.1016/j.neuron.2021.05.025.
K. T. Baldwin et al., “HepaCAM controls astrocyte self-organization and coupling,” Neuron, vol. 109, no. 15. Elsevier, p. 2427–2442.e10, 2021.
Baldwin KT, Tan CX, Strader ST, Jiang C, Savage JT, Elorza-Vidal X, Contreras X, Rülicke T, Hippenmeyer S, Estévez R, Ji R-R, Eroglu C. 2021. HepaCAM controls astrocyte self-organization and coupling. Neuron. 109(15), 2427–2442.e10.
Baldwin, Katherine T., et al. “HepaCAM Controls Astrocyte Self-Organization and Coupling.” Neuron, vol. 109, no. 15, Elsevier, 2021, p. 2427–2442.e10, doi:10.1016/j.neuron.2021.05.025.