p53-dependent suppression of uridine phosphorylase gene expression through direct promoter interaction
Autor: | D, Zhang, D, Cao, R, Russell, G, Pizzorno |
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Rok vydání: | 2001 |
Předmět: |
Uridine Phosphorylase
Base Sequence Transcription Genetic Molecular Sequence Data Chromosome Mapping 3T3 Cells Ribonucleotides Gene Expression Regulation Neoplastic Mice Pyrimidines Tumor Cells Cultured Animals Gene Silencing RNA Messenger Tumor Suppressor Protein p53 Promoter Regions Genetic Protein Binding |
Zdroj: | Cancer research. 61(18) |
ISSN: | 0008-5472 |
Popis: | Uridine phosphorylase (UPase) is a key enzyme in the pyrimidine salvage pathway. It reversibly catalyzes the catabolism of uridine to uracil; controls the homeostatic regulation of uridine concentration in plasma and tissues; and plays a role in the intracellular activation of 5-fluorouracil. We cloned the murine UPase gene promoter, a 1703-bp fragment, and determined the transcription initiation sites located at +1 and +92 bp of the cDNA sequence. Through transient expression analysis of the 5'-flanking region of UPase gene, we have evaluated the promoter activity for a series of fragments with 5'- to 3'-deletion in murine breast cancer EMT-6 cells and immortalized murine fibroblast NIH 3T3 cells. Cotransfection of the UPase promoter constructs (from -1619 to -445) containing p53 binding motif with the wild-type p53 construct resulted in a significant reduction of luciferase activity; however, this effect disappeared with the additional deletion of the -445 to -274 sequence to suggest the existence in this promoter region of a putative p53 recognition element. Similar cotransfection in murine embryo fibroblasts p53-/- confirmed the inhibitory role of p53 on the UPase promoter activity. The specificity of the interaction is demonstrated by nuclear protein-specific binding to the putative p53 recognition sequence using gel mobility shift assay and DNase I footprinting analysis. These data indicate the UPase gene is a novel target of p53, and its expression is down-regulated by p53 at the promoter level. |
Databáze: | OpenAIRE |
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