Myelin/oligodendrocyte glycoprotein expression during development in normal and myelin-deficient mice.

The myelin/oligodendrocyte glycoprotein (MOG) is identified by monoclonal antibody 8-18C5. MOG is localized on the surface of myelin and oligodendrocyte processes. Recently, several studies have shown that MOG plays an important role as a target for antibody-induced demyelination. In the present study, we investigated MOG expression in the brains of normal and myelin-deficient (mld) mutant mice during development. By gel electrophoresis and immunoblotting, we observed the developmental pattern of two closely migrating bands, with apparent molecular masses of 26 and 28 kilodaltons. Their concentrations increased coordinately during the most active phase of myelin and myelin basic protein (MBP) synthesis. Between 20 and 25 days of age, the MOG developmental pattern superimposed that of MBP as well as myelin yields. In mld mutant mice, which are affected by a severe deficit of MBP synthesis, MOG was present at reduced levels (40% of controls at 60 days of age). At 85 days of age, mld mice exhibited increased concentrations of MBP, and myelin was better compacted. At this age, MOG concentrations increased and reached 70% of controls. These results suggest that MOG could play a role in the maintenance or completion of the myelin sheath. Its expression level may be modulated by the presence of compact myelin and/or MBP in the myelin sheath.