Genomic structure and promoter analysis of the ecto-phosphodiesterase I gene (PDNP3) expressed in glial cells

PDNP (phosphodiesterase I/nucleotide pyrophosphatase) is one of a series of ectoenzymes that are involved in hydrolysis of extracellular nucleotides. PDNP possesses ATPase (EC 3.6.1.3) and ATP pyrophosphatase (EC 3.6.1.8) act ivities. Mammalian PDNP consists of three closely related family proteins ( PDNP1, -2, and -3), and they are expressed in different cell types and at d ifferent developmental stages. Rat PDNP3 is expressed in a subset of immatu re glial cells and in the alimentary tract. Human PDNP3 is expressed in gli oma cells, prostate, and uterus, but not in the alimentary tract. We have c loned genomic DNA containing the whole coding region of the human PDNP3 gen e and determined its exon-intron structure. The human PDNP3 gene spans over 60 kb and is organized into 25 exons and 24 introns. We determined the nuc leotide sequence of the 5'-flanking region of human and rat PDNP3 genes. Th e upstream region of both species lacks a canonical TATA box and contains a putative binding site for CCAAT enhancer-binding proteins near the transcr iption start site. Promoter activity analysis of the 5'-flanking region rev ealed that the sequence around the CCAAT box is required for its transcript ional activity in 9L rat glioma cells. A gel shift assay demonstrated that 9L nuclear extract contains proteins that bind to this region. (C) 1999 Els evier Science B.V. All rights reserved.