Seminar Abstract: Myelin sheaths comprise compacted layers of membrane wrapped around axons. Each sheath, if 'unwrapped', has a cytoplasm-filled space at its perimeter. Transmission electron microscopy reveals that this space contains microtubules and organelles; however, whether these are developmental remnants or serve a specific function remains unknown. Live imaging of myelinating oligodendrocytes in mice showed microtubule-dependent organelle transport within myelin sheath cytoplasmic spaces. Further, movement of myelin-located peroxisomes was modulated by neuronal electrical activity, in vitro and in vivo. Loss of oligodendroglial KIF21B and/or CNP in vivo led to the apparent stasis of myelin organelles and secondary axon pathology. We, thus, propose the acronym TRAM (transport route across myelin), defining the continuous cytoplasmic network in oligodendrocytes and myelin. This system, comprising the inner and outer tongues and paranodal loops, spans compact myelin and enables transport of metabolites and organelles between the oligodendrocyte soma and the periaxonal space.

Biosketch: Professor Julia Edgar is Professor of Neurobiology and Head of the School of Infection & Immunity at the University of Glasgow, where she leads the Axo-glial Research Group. Her research focuses on the interactions between oligodendrocytes and axons, particularly the mechanisms by which myelin-forming cells support neuronal function and protect against axonal degeneration. Her work has important implications for understanding neurological disorders, including multiple sclerosis and leukodystrophies.

Professor Edgar obtained her PhD from the University of Edinburgh, supported by a Wellcome Trust Prize Studentship. She subsequently joined the University of Glasgow, where she was awarded a Multiple Sclerosis Society Fellowship before being appointed Lecturer in Neuroscience in 2009. She also spent two years as a staff scientist at the Max Planck Institute of Experimental Medicine in Göttingen, Germany, before returning to Glasgow to establish her research group. Her research combines cellular and molecular approaches with advanced imaging to investigate axon-glial interactions, myelin biology and mechanisms of neurodegeneration, with particular emphasis on the contribution of inflammation to neurological disease.