Multiple Sclerosis (MS) is a progressive inflammatory demyelinating disease that affects the central nervous system (CNS), and it is considered the most common non-traumatic debilitating neurologic disease in young adults. Based on recent advances in the understanding of the disease mechanisms underlying MS, it has become evident that clinical relapse and progressive accumulation of disability are driven by different pathological processes. Importantly, current therapies for MS mostly target the chronic inflammatory component mediating clinical relapse, and they are effective in modifying the disease course and in managing symptoms. Relapse-independent disease progression, on the other hand, is to a large extent driven by the degeneration of chronically demyelinated and hence more vulnerable axons. Hence, myelin restoration has emerged as a promising strategy toward a regenerative treatment for MS. At present, however, we are only at the very beginning of developing practical approaches with the potential to promote myelin regeneration in vivo in the human brain, and therapeutic agents that limit progressive disease mechanisms and promote CNS repair remain an important unmet challenge in MS clinical practice. Thus, there is a critical need to broaden the scope of druggable targets to advance the design of myelin regenerating therapies for MS. To address this need, we propose here to explore the role of a novel glutamate-driven signaling pathway that is initiated in maturing oligodendrocytes (OLGs), the myelinating cells of the central nervous system (CNS), through activation of the sodium-dependent glutamate transporter GLT-1, also known as excitatory amino acid transporter 2 (EAAT2) or solute carrier family 1 member 2 (SLC1A2). In MS, and particularly in progressive MS, there is evidence that this pathway is impaired, thereby limiting efficient myelin repair. Importantly, our preliminary data provide compelling evidence that loss of GLT-1 in maturing OLGs limits myelin repair in the cuprizone model that reflects features of particularly progressive stages of MS. In light of the glutamate homeostasis regulating role of GLT-1 in astrocytes, characterizing mechanisms downstream of GLT-1 activation in maturing OLGs represents a critical step toward the identification of potential therapeutic targets. In this context, our preliminary data point toward a critical role of the small GTPase RhoB and its unique functional roles in regulating endosomal and myelin protein trafficking mechanisms. By characterizing the role of a promising new signaling cascade and by investigating a molecular mechanism targeting more mature OLGs rather than OLG progenitor cells, our studies address major gaps in the field. Notably, there is increasing evidence for an involvement of Rho GTPase signaling and protein targeting in CNS myelin repair, and Rho GTPases emerge as promising therapeutic targets. Thus, in the long-term, the proposed studies are anticipated to provide nov...