EXPRESSION OF THE MYELIN BASIC-PROTEIN GENE LOCUS IN NEURONS AND OLIGODENDROCYTES IN THE HUMAN FETAL CENTRAL-NERVOUS-SYSTEM

The myelin basic protein (MBP) gene locus is composed of two overlappi ng transcription units that share all of the MBP exons. One of these t ranscription units expresses the MBPs and the other expresses a family of proteins structurally related to the MBPs. This second transcripti on unit is called the Golli gene, and the entire complex is called the Golli-mbp gene. In this study, the expression of the Golli gene was e xamined in the human fetal central nervous system (CNS). By using reve rse transcriptase-polymerase chain reaction cloning we have identified eight new members of the Golli gene family of transcripts expressed i n the human CNS. Golli gene expression was examined by in situ hybridi zation and immunohistochemistry, and surprisingly, Golli products were found to be expressed in neurons as well as oligodendrocytes. Further more, the subcellular distribution of Golli immunoreactivity in fetal spinal cord interneurons shifted between the various laminae. Golli pr otein was localized within the nuclei of interneurons in the posterior horn, but was found in the cell bodies and processes of interneurons in the anterior horn. Within oligodendrocytes, Golli protein was detec ted in the cell bodies and processes, including processes which were w rapping axonal segments. Golli mRNA expression was also observed in ne urons within the cerebral cortex between 18 and 20 weeks postconceptio n, prior to myelination of this brain region. During this period, ther e was a striking developmental increase in the numbers and in the loca tions of neurons expressing Golli mRNAs within the cortical plate. The diverse distribution of Golli proteins within neurons and oligodendro cytes indicates that their function is quite different from that of th e MBPs to which they are closely related. (C) 1996 Wiley-Liss, Inc.