Factor binding sites within the antisilencer/enhancer region of the myelin proteolipid protein gene are important for transcriptional activity in cultured oligodendroglial cells

Abstract

The first intron of the myelin proteolipid protein (Plp) gene contains a positive regulatory region known as the antisilencer/enhancer (ASE) that is located between nucleotides 1083 and 1177 of the intron and is sufficient to restrict high‐level expression of the gene to oligodendrocytes in mice. To identify critical transcriptional control elements within the ASE, we have created a series of twelve non‐overlapping 8 bp linker scan mutations across the ASE region. These mutant ASE fragments were inserted in both orientations into a Plp‐lacZ fusion gene containing a shortened form of intron 1 that lacked the ASE. Relative transcriptional activities of these PLP‐lacZ constructs were assessed indirectly by measuring the β‐galactosidase activities in extracts of transiently transfected oligodendroglial (N20.1) cells. Five of the mutants with linkers inserted near the center of the ASE demonstrated reduced activity (10–50% of wild‐type levels). This effect was relatively independent of the orientation of the ASE inserted into the Plp‐lacZ constructs, consistent with the function of this region as a transcriptional enhancer. LS mutations at these same positions were previously shown to interfere with the binding of factors present in nuclear extracts of N20.1 cells, suggesting that these factors may be important in the oligodendrocyte‐specific regulation of the Plp gene. Supported by NIH grant P20 RR‐16460.