title: P53 family members modulate the expression of PRODH, but not PRODH2, via intronic p53 response elements.
abstract: The tumor suppressor p53 was previously shown to markedly up-regulate the expression of the PRODH gene, encoding the proline dehydrogenase (PRODH) enzyme, which catalyzes the first step in proline degradation. Also PRODH2, which degrades 4-hydroxy-L-proline, a product of protein (e.g. collagen) catabolism, was recently described as a p53 target. Here, we confirmed p53-dependent induction of endogenous PRODH in response to genotoxic damage in cell lines of different histological origin. We established that over-expression of TAp73β or TAp63β is sufficient to induce PRODH expression in p53-null cells and that PRODH expression parallels the modulation of endogenous p73 by genotoxic drugs in several cell lines. The p53, p63, and p73-dependent transcriptional activation was linked to specific intronic response elements (REs), among those predicted by bioinformatics tools and experimentally validated by a yeast-based transactivation assay. p53 occupancy measurements were validated in HCT116 and MCF7 human cell lines. Conversely, PRODH2 was not responsive to p63 nor p73 and, at best, could be considered a weak p53 target. In fact, minimal levels of PRODH2 transcript induction by genotoxic stress was observed exclusively in one of four p53 wild-type cell lines tested. Consistently, all predicted p53 REs in PRODH2 were poor matches to the p53 RE consensus and showed very weak responsiveness, only to p53, in the functional assay. Taken together, our results highlight that PRODH, but not PRODH2, expression is under the control of p53 family members, specifically p53 and p73. This supports a deeper link between proteins of the p53-family and metabolic pathways, as PRODH modulates the balance of proline and glutamate levels and those of their derivative alpha-keto-glutarate (α-KG) under normal and pathological (tumor) conditions.
authors.affiliation: Department of Biotechnology and Life Sciences, DBSV, University of Insubria, Varese, Italy.
authors.forename: Ivan
authors.initials: I
authors.lastname: Raimondi
authors.forename: Yari
authors.initials: Y
authors.lastname: Ciribilli
authors.forename: Paola
authors.initials: P
authors.lastname: Monti
authors.forename: Alessandra
authors.initials: A
authors.lastname: Bisio
authors.forename: Loredano
authors.initials: L
authors.lastname: Pollegioni
authors.forename: Gilberto
authors.initials: G
authors.lastname: Fronza
authors.forename: Alberto
authors.initials: A
authors.lastname: Inga
authors.forename: Paola
authors.initials: P
authors.lastname: Campomenosi
mesh_terms: D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D004249:DNA Damage / Q000235:genetics; D045325:HCT116 Cells; D006801:Humans; D007438:Introns / Q000235:genetics*; D061986:MCF-7 Cells; D008969:Molecular Sequence Data; D011394:Proline Oxidase / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D055550:Protein Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; C115051:TP63 protein, human; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D011394:Proline Oxidase; C582834:PRODH protein, human