Dorsal root ganglia neuron specific promoter activity of the rabbit beta-galactoside alpha 1,2-fucosyltransferase gene

The rabbit H-blood type alpha 1,2-flucosyltransferase (RFT-I), gene and its biosynthetic products, H antigens (Fuc alpha 1,2Gal beta), are abundantly expressed in a subset of dorsal root ganglia (DRG) neurons. To investigate the regulatory mechanisms for the RFT-I gene expression, we determined the genomic structure and promoter activity of this gene. PCR amplification of the 5' cDNA end analysis revealed two transcriptional start sites, 498 and 82 nucleotides upstream of the translational initiation codon, the latter s ite yielding a major 3.1-kb transcript specifically expressed in DRG, as re vealed by Northern blotting. Promoter analysis of the 5'-flanking region of the RFT-I gene using a luciferase gene reporter system demonstrated strong promoter activity in PC12 cells, which express the rat H-type alpha 1,2-fu cosyltransferase gene, and Neuro2a mouse neuroblastoma cells. Deletion anal ysis revealed the 704-base pair minimal promoter region flanking the transl ational initiation codon, for which two distinct promoter activities were d etected and differentially used in PC12 and Neuro2a cells, The minimal prom oter region contained a GC-rich domain (GC content 80%), in which a Spl bin ding sequence and a GSG-like nerve growth factor-responsive element were fo und, but lacked TATA- and CAAT-boxes. Promoter analysis with a primary cult ure of DRG neurons demonstrated that the minimal promoter region of the RFT -I gene was sufficient for the expression of a reporter gene in DRG neurons . We conclude that the TATA-less GC-rich minimal promoter region of the RFT -I gene controls DRG small neuron-specific expression of the RFT-I gene.