Identification of a Mouse Thiamine Transporter Gene as a Direct Transcriptional Target for p53

Abstract

p53 tumor suppressor is a transcription factor that functions, in part, through many of its downstream target genes. We have identified a p53-inducible gene by performing mRNA differential display on IW32 murine erythroleukemia cells containing a temperature-sensitive p53 mutant allele, tsp53 . Sequence analysis of the fulllength cDNA revealed its identity as the mouse homologue of the human thiamine transporter 1 (THTR-1). Induction of the mouse THTR-1 (mTHTR-1) mRNA was detectable as early as 1 h at 32.5°C; upon shifting back to 38.5°C, mTHTR-1 transcript was rapidly degraded with a half-life of less than 2 h. Elevation of mTHTR-1 expression was found in DNA damage-induced normal mouse embryonic fibroblast cells, but not in p53 ؊/؊ mouse embryonic fibroblast cells, suggesting that mTHTR-1 induction was p53-dependent. A region within the first intron of the mTHTR-1 gene bound to p53 and conferred the p53-mediated transactivation. Furthermore, increased thiamine transporter activities were found in cells overexpressing mTHTR-1 and under conditions of DNA damage or p53 activation. Our findings indicate that p53 may be involved in maintaining thiamine homeostasis through transactivation of THTR-1.

NAD+ Modulates p53 DNA Binding Specificity and Function

“…Though thiamine is not reported to modulate DNA damage responses, p53 activates transcription of a murine thiamine transporter (31). However, in addition to regulating p53, as reported here, niacinamide affects other proteins that are involved in cellular decisions of apoptosis and senescence, including PARP (19) and SIR2 (1,33,53).…”

p53 Negatively Regulates Transcription of the Pyruvate Dehydrogenase Kinase Pdk2

“…For instance, in mice p53 promotes the expression of the thiamine transporter (29). Greater uptake of thiamine increases cellular thiamine pyrophosphate, which is a cofactor of the Pdc and which is also an inhibitor of phosphorylation of Pdc by Pdk2 (30).…”

Increased Sensitivity to UV Radiation in Mice with a p53 Point Mutation at Ser389

“…The sequence of the supplied probe used was 5Ј AGC TGG ACA TGC CCG GGC ATG TCC 3Ј, homologous to the p53 binding consensus sequence, 5Ј PuPuPuC(A/T)(A/T)G PyPyPy 3Ј, as described earlier (14,30). Binding reactions were run on a native 4% polyacrylamide gel (200 V for 1.5 h) with 0.25ϫ Tris-borate-EDTA as a running buffer.…”