IDENTIFICATION OF NOVEL MESSENGER-RNAS EXPRESSED IN OLIGODENDROCYTES

To identify new proteins, which are expressed in oligodendrocytes and which may have a functional role in myelination, a rat oligodendrocyte cDNA library was screened using differential and subtractive screenin g techniques. Ten clones that have elevated levels of expression in br ain were isolated. Two of these clones were characterized further and one clone, pC26.H2, was found to be closely related to mouse stearoyl- CoA desaturase 2 (SCD2), which catalyzes the synthesis of unsaturated fatly acid. From Northern blot and in situ hybridization studies, SCD2 mRNA was expressed primarily in brain with lower levels found in lung and spleen. In brain sections, SCD2 mRNA was found primarily in oligo dendrocytes, although mRNA was detected at a low level in neurons, in particular in Purkinje cells in the cerebellum. Northern blot analysis of the other clone, p973.HB, indicated that it was expressed more sel ectively in brain. In mixed glial cultures oligodendrocytes were the o nly cells that expressed this mRNA, whereas in brain, neurons expresse d this mRNA at a higher level than in oligodendrocytes. This clone is being actively pursued because of its unique expression exclusively in oligodendrocytes and neurons.