Metabolic coupling of oligodendroglia and endothelial cells through cell-specific lactate dehydrogenase A - PROJECT SUMMARY/ABSTRACT Myelin is vital to neuron health and function, as it provides insulation and metabolic and trophic support to axons. In many neurological diseases, such as multiple sclerosis, myelin is damaged and lost. In such cases, myelin repair is often incomplete, leaving axons chronically demyelinated. This is thought to leave axons susceptible to subsequent degeneration. Thus, finding novel strategies to promote remyelination is of the utmost importance in treating demyelinating diseases. Myelin formation is a metabolically demanding process as oligodendrocyte progenitors (OPCs) differentiate and expand their membranes. During developmental myelination, OPCs signal to promote angiogenesis, helping to build a robust vascular network capable of delivering the metabolites necessary to support OPC differentiation and myelin formation. However, how adult OPCs meet their metabolic demands during active remyelination after white matter injury remains unknown. This application focuses on the role of lactate in the metabolic coupling of OPCs with CNS vasculature in the context of active remyelination. The preliminary data presented here demonstrate that lactate dehydrogenase A (LDHA), the enzyme for converting pyruvate to lactate during glycolysis, in OPCs is necessary for proper angiogenesis and myelination during development. Further, mouse models of demyelination experience vascular remodeling and expansion during remyelination, which is coupled with increased expression of the lactate transporter, MCT1. This proposal will test the hypothesis that during remyelination, OPC-encoded Ldha promotes vascular network expansion through endothelial-MCT1 and lactate uptake, and that the resulting vascular network supports functional axonal remyelination and conduction. This will be done using a wide array of genetic, pharmacological, and proteomic approaches focusing on understanding how OPC-Ldha (Aim1) and endothelial-MCT1 (Aim 2) function to coordinate CNS vascular remodeling and remyelination. In the first aim, I will use the Cre-lox system to delete Ldha specifically in oligodendroglia. Using the cuprizone model of demyelination, I will assess vascular remodeling and functional remyelination in control and Ldha-knockout mice. I will also isolate mitochondria from the oligodendroglia for use in proteomic experiments in order to determine the metabolic role of LDHA in remyelination. In Aim 2, I will use shRNA to knock down Mct1 specifically in endothelial cells. This will be done in the Myrf-knockout model of demyelination. These mice will be assessed for alterations in remyelination and brain vascularization. The completion of the experiments and training plan outlined in this application will provide exceptional training opportunities that will enhance and expand my technical skills and further my knowledge of glial and vascular biology. It will also produce the data necessary for future funding applications that will allow me to carve out a research niche as an independent investigator.
