Cell-specific expression of the mouse glial fibrillary acidic protein gene: identification of the cis- and trans-acting promoter elements for astrocyte-specific expression.

We have determined the whole promoter sequence and the transcriptional startpoint of the mouse glial fibrillary acidic protein (GFAP) gene and characterized the promoter function. We found that the cis elements for astrocyte specific expression are located within 256 bp from the transcription startpoint. We defined by DNase I footprinting assay three trans-acting factor binding sites (GFI, GFII, and GFIII) using brain or C6 astrocytoma nuclear extracts. GFI, GFII, and GFIII have AP-2, NFI, and cyclic AMP-responsive element motifs, respectively. Mutations in GFII drastically decreased the promoter activity. Base substitution in GFI and GFIII abolished the cell-specific expression, resulting in the GFAP promoter expression even in some non-GFAP-producing cells.