CHARACTERIZATION OF PAX-6 AND HOXA-1 BINDING TO THE PROMOTER REGION OF THE NEURAL CELL-ADHESION MOLECULE L1

The neural cell adhesion molecule L1, a member of the immunoglobulin s uperfamily, mediates cell interactions in the developing and regenerat ing nervous system of mammals and is also detectable in the immune sys tem and in the epithelia of intestine, skin, lung, and kidney. This di verse pattern of expression begs the question as to the regulatory mec hanisms underlying transcription of the L1 gene. We demonstrate here t hat the paired domain and homeodomain containing Pax-6 protein binds t o three different sites in the promoter region of the L1 gene. The pro moter proximal binding site is also recognized by Hoxa-1 and Lies appr oximately 60 bp upstream from the transcription start site only few ba se pairs upstream of a putative binding site for the TFII-I transcript ion initiation factor. On the basis of this sequence, we have characte rized the binding of Pax-6 and explored two modes of its DNA binding a ctivities.