Cloning and expression of the mouse deoxyuridine triphosphate nucleotidohydrolase gene: differs from the rat enzyme in that it lacks nuclear receptor interacting LXXLL motif.

We have previously reported the cloning of rat deoxyuridine triphosphate nucleotidohydrolase (dUTPase) cDNA and demonstrated that the full-length protein as well as the N-terminal 62-amino acid peptide interacts with peroxisome proliferator-activated receptor alpha (PPARalpha). We now report the cloning of mouse dUTPase cDNA and show that it contains a 162-amino acid open reading frame, encoding a protein with a predicted Mr of 17,400 and differs from rat cDNA, which contains additional 43 amino acids at the N-terminal end. Unlike rat dUTPase, mouse dUTPase failed to bind PPARalpha. An evaluation of 205 amino acid containing rat dUTPase cDNA revealed that the N-terminal 43 extra amino acid segment contains an LXXLL signature motif, considered necessary and sufficient for the binding of several cofactors with nuclear receptors, and its absence in murine dUTPase possibly accounts for the differential binding of these enzymes to PPARalpha. In situ hybridization and immunohistochemical studies revealed that, in the adult mouse, dUTPase is expressed at high levels in proliferating cells of colonic mucosa, and of germinal epithelium in testis. At 9.5-day mouse embryonic development, dUTPase expression is predominantly in developing neural epithelium, and hepatic primordium, and in later developmental stages (11.5-, 13.5-, and 15.5-day embryo), the expression began to be localized to the liver, kidney, gut epithelium, thymus, granular layer of the cerebellum, and olfactory epithelium. We also show that the murine dUTPase gene comprises 6 exons and the 5'-flanking region of -1479 to -27, which exhibited high promoter activity, contains a typical TATA box and multiple cis-elements such as Sp-1, AP2, AP3, AP4, Ker1, RREB, and CREB binding sites. These observations suggest the existence of variants of dUTPase, some of which may influence nuclear receptor function during development and differentiation, in addition to catalyzing the hydrolysis of dUTP to dUMP.