The meninges encase the CNS from its earliest stages of development and persist as a protective covering for the adult brain. Many studies show the meninges have vital roles in controlling developmental neurogenesis and neuronal migration and congenital defects in human brain development can arise from meningeal defects. Despite this, the cellular and molecular mechanisms that control formation of the meninges are largely unknown. A major limitation to progress on studying the meninges is lack of modern, molecular characterization of meningeal fibroblasts and other important cellular residents of the developing meninges. This has been difficult to obtain due to the intermingling of meningeal fibroblasts with vascular and immune cell populations, limiting the usefulness of `bulk' transcriptional or proteomic analysis of the developing meninges. To overcome these obstacles, we will use single-cell RNA-sequencing along with the Col1a1-GFP mouse line that we have found can be used to enrich for meningeal fibroblasts. In this proposal, we will use these techniques with mice that lack the transcription factor Foxc1, previously shown by us and others to be required for meninges development and function. This data will be used to 1) create a molecular signature of all meningeal cell populations during development and 2) identify how gene expression in these populations changes in Foxc1 mutants in which meningeal development is impaired. This approach will provide important knowledge of meninges `assembly', a complex process that includes formation of the fibroblast layers, the establishment of blood and lymphatic plexuses, immune cell populations and, eventually, a neural stem cell niche. Important for our focus on Foxc1, we will obtain single cell resolution of the impact of Foxc1 loss on separate meningeal fibroblast populations. From this we can develop new hypotheses about how loss of Foxc1 impairs development and function of the meningeal layers that is so devastating to brain development. Finally, these data will provide much needed characterization of the meninges that can be a resource for researchers studying meninges-related structure, process, disease or malformation.
Neurodevelopmental disorders resulting from defects in neurogenesis and neuronal migration can cause lifelong cognitive and motor impairments. Understanding how these processes go awry is important for developing therapeutic strategies to help patients with these disorders. This proposal is focused on the meninges, a vital protective covering for the CNS AND a key source for signals required for CNS development. Our goal is to better understand the signaling that goes on between the meninges and developing brain and an important step we take in this proposal is to generate better molecular characterization of the meninges.
