FUNCTIONAL-ORGANIZATION OF THE PROMOTER REGION OF THE MOUSE F3 AXONALGLYCOPROTEIN GENE

F3 is a developmentally regulated adhesive glycoprotein expressed by s ubpopulations of central and peripheral neurons which mediates neurite growth and fasciculation via cis- and trans-interactions with cell-su rface or matrix components. We previously reported on the characteriza tion of the F3 gene 5' flanking region in which we identified promoter and enhancer elements. Here, we report on the functional organization of the F3 gene regulatory regions. We show that the F3 promoter is bu ilt of linearly arranged positive and negative elements scattered thro ugh the 5' flanking region of the F3 gene and the 1st exon (exon 0). N eural-and cell type-specific expression of F3 appears to be governed b y elements located in the most proximal promoter region which includes a neural-specific enhancer. In retardation assays, all these cis-acti ng elements bind nuclear proteins, three of which interact with the id entified enhancer element while a single species interacts with sequen ces located within exon 0. Some of these proteins are also specificall y expressed within the brain, indicating that they could correspond to neural-specific trans-acting factors. Elements located immediately up stream of the cell type-specific enhancer and within exon 0 are respon sible for regulation of F3 expression by cAMP and retinoic acid.