Mechanisms regulating Meningeal Development and Function

ABSTRACT/PROJECT SUMMARY The meninges, a protective layer ensheathing the Central Nervous System (CNS), is a highly vascularized, complex tissue that serves as the primary site for equilibration of cerebrospinal fluid (CSF). CSF, a transparent, colorless fluid that recirculates throughout the CNS, supports brain buoyancy, prevents vascular and neuronal collapse, and provides buffering against mechanical injury. Given the functional importance of CSF for CNS homeostasis, the clearance of metabolic waste from this fluid compartment is carried out as a nearly constant process. This waste removal process relies heavily on groups of vascular- associated, perivascular cells within the meninges that filter the byproducts from the CSF and transport them into circulation via the lymphatic system for ultimate disposal. Hence, the interaction between meningeal cells and the vascular system is crucial to safeguard brain homeostasis. Some forms of neurodegeneration have been linked with a decline in homeostasis and an increase in metabolic waste accumulation in an age-, diet- or pathogenic infection-dependent manner. Understanding vascular- associated meningeal cells make-up, developmental origin, genetic regulation and function is an important long-term undertaking to fully grasp how neurodegeneration occurs in response to these conditions. The amenability of the zebrafish for live imaging represents a remarkable advantage over other models to study meningeal development in vivo. In Aim 1, I will use newly developed transgenic lines labeling pan- meningeal and meningeal perivascular cell populations in vivo to uncover the developmental origin of these cells using a combination of high resolution confocal imaging for lineage tracing studies, Transmission Electron Microscopy to characterize their cellular structures, and single cell and “RiboTag” RNA- sequencing to identify gene programs regulated in meningeal populations. Aim 2 will uncover the functions that meningeal cells play in supporting CNS homeostasis and maintenance. Analysis will be done utilizing readily available mutants that present defects in meningeal development. In addition, as an unbiased approach, I will utilize a forward genetic mutagenesis screen to uncover genes required for proper meningeal development and function. Lastly, complementary in vivo high resolution confocal imaging and in vitro cell culture assays will be utilized to uncover biochemical changes in meningeal cells resulting from age, diet, and infection in both wild type and mutant zebrafish populations (Aim 3). These aims are designed to expand the current knowledge of meningeal cellular components, genetic signals controlling their development, and a better understanding of their interaction with the vasculature. This proposal offers a foundational niche in the vascular developmental biology field through which I can launch a future tenure- track research faculty position.