Membrane traffic in myelinating oligodendrocytes

In the central nervous system (CNS), the myelin sheath is synthesised by ol igodendrocytes as a specialised subdomain of an extended plasma membrane, r eminiscent of the segregated membrane domains of polarised cells. Myelinati on takes place within a relatively short period of time and oligodendrocyte s must have adapted membrane sorting and transport mechanisms to achieve su ch a high rate of myelin synthesis and to maintain the unique organisation of the myelin membrane. In adult life, maintenance of the functional myelin sheath requires a carefully orchestrated balance of myelin synthesis and t urnover. Imbalance in these processes may cause dys- or demyelination and d isease. This review summarises what is currently known about myelin protein trafficking and mistrafficking in oligodendrocytes. We also present data d emonstrating distinct transport pathways for myelin structural proteins and the expression of SNARE proteins in differentiating oligodendrocytes. Myel inating glial cells may well serve as a model system for studying general a spects of membrane trafficking and organisation of membrane domains. (C) 20 01 Wiley-Liss, Inc.