Clonal analysis of gliogenesis in the cerebral cortex

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The cerebral cortex critically relies on balanced production of neurons and glia during embryonic and early postnatal development. Recently developed clonal lineage analysis has revealed the behavior of neural stem cells (NSCs) giving rise to neurons in the cerebral cortex with unprecedented single-cell resolution. However, the formation of glia by NSCs remains unclear and has yet to be systematically investigated using these new technologies. Gliogenesis is critical for proper neuronal functions and when disrupted, it can result in various neurological diseases. Reconstructing how glia are generated from individual NSCs and organized in the cortex during development is essential to understand the structure-function relationships and how they can be modulated by clone-specific factors. We have established a genetically-based single-cell lineage tracing technique utilizing MADM (Mosaic Analysis with Double Markers) mice to label NSCs in the developing cortex and begin to address this knowledge gap. Using this method we have found two distinct populations of glia that occupy different territories of the cortex and its related structure the hippocampal formation. The goal of the proposed research is to reconstruct, quantify, and mathematically model the behavior of individually labeled NSCs in vivo. We will use the power of this labeling method to also screen for gene expression of glial clones at single cell resolution, which all together will help us decipher the general principles organizing glial clones in the cortex, and define how clonal siblings interact with each other. We will test the role of some of the identified genes in generation of glial clones in the cortex, which will further help define the biological system underlying principles of gliogenesis. Successful completion of our study will result in a comprehensive map of single NSCs and their glial progeny in various cortical regions. Our approach will also establish a platform for detailed quantitative and computational analysis of gliogenesis, glial diversity, and their potential for regenerative approaches in the cortex. Potential for Broader Impact Our approaches to understand how important constituents of the brain, the glial cells, develop have wide implications. Disruption of glial development is the root of a range of pathological conditions in the brain. Therefore, understanding the basic principles and cellular mechanisms that control gliogenesis is critical to appreciate not only how healthy development may be controlled by systematic production of glial cells, but also how abnormalities in gliogenesis may lead to devastating neurodevelopmental disorders and brain tumors.