Developmental expression of the murine Mopb gene

In this report we describe the developmental expression of the murine (Mobp) gene encoding myelin‐associated oligodendrocytic basic protein. We have characterized three Mobp cDNA clones which have been used as probes. Murine Mobp splice variant‐1 (mmsv‐1), a portion of 3′ untranslated region (UTR), is homologous to 3′ UTR sequences found in the rat Mobp splice variants rOP1, Mobp81‐A and Mobp‐99. The mmsv‐2 sequence, encoding 81 amino acids, closely resembles the rat Mobp81‐A splice variant. The mmsv‐3 cDNA, encoding 170 amino acids corresponding closely to the rat rOPRP1 splice variant, detects a single mRNA species present in low levels from E12 onward, suggesting this MOBP may have a function alternative or additional to involvement in myelin formation. The mmsv‐1 probe detects an mRNA species abundantly expressed in the postnatal central nervous system (CNS) but barely detectable at E18. This mRNA is located initially in the cell bodies of oligodendrocytes, moving distally into their processes as myelination proceeds. The most abundant mmsv(s) in the adult CNS are present at detectable levels after expression of the myelin basic protein (Mbp) gene and marginally after or coincident with the proteolipid protein (Plp) gene. The level of the abundant, late‐expressed mRNA correlates closely with the capacity to form myelin and the maturity of oligodendrocytes, as shown in two hypomyelinated mutants, rumpshaker and jimpy, which represent mildly and severely affected phenotypes, respectively. J. Neurosci Res. 49:133–143, 1997. © 1997 Wiley‐Liss, Inc.