American Journal of Physiology-Renal Physiology · 2003 · 15 citations · 23 references
Life SciencesBiochemistryMolecular BiologyGene ExpressionRenal PathophysiologyTranscriptional RegulationMrna StabilityPhosphate HomeostasisRenal Molecular PhysiologyRenal PhysiologyRenal TransportersRna-binding ProteinsCis-regulatory Element FunctionCis-regulatory Element RegulationGreen Fluorescent Protein ReportersNapi CotransportersPhosphate Co-transportersRenal Adaptation To Phosphate LoadRenal Phosphate TransportReporter Gene Construction
Hypophosphatemia leads to an increase in Na(+)-P(i) cotransporter (NaPi-2) mRNA levels. This increase is posttranscriptional and correlates with a more stable transcript mediated by the terminal 698 nt of the NaPi-2 mRNA. A 71-nt binding element was identified with renal proteins from rats fed control and low-P(i) (-P(i)) diet. The binding of -P(i) renal proteins to this transcript was increased compared with control proteins. The functionality of the cis element was demonstrated by an in vitro degradation assay. -P(i) renal proteins stabilized transcripts that included the cis element compared with control renal extracts. The full-length NaPi-2 transcript, but not control transcripts, was stabilized by -P(i) extracts. Insertion of the binding element into green fluorescent protein (GFP) as a reporter gene decreased chimeric GFP mRNA levels in transfection experiments. Our results suggest that the protein-binding region of the NaPi-2 mRNA functions as a cis-acting instability element. In hypophosphatemia there is increased binding to the cis-acting element and subsequent stabilization of NaPi-2 mRNA.
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Laurent Beck, Andrew C. Karaplis, Norio Amizuka et al. · Proceedings of the National Academy of Sciences · 1998 · 599 citations · Full text