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An uORF in p53 mRNA Regulates Translation and mRNA Stability
Author(s) -
Carastro L. Michael,
Gandikal Naz,
Brucklacher Robert,
Lazarus Philip
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a652-a
Subject(s) - upstream open reading frame , five prime untranslated region , translation (biology) , biology , messenger rna , nonsense mediated decay , microbiology and biotechnology , genetics , rna , gene , rna splicing
A p53 mRNA 5′‐leader encodes an upstream open reading frame (uORF). Translation of some uORFs triggers nonsense‐mediated mRNA decay (NMD). NMD is a translation‐ and PI3‐like kinase‐dependent mRNA degradation process in eukaryotic cells. Data from analyses of human p53 5′‐leader sequences demonstrate that (1) translation of a downstream reporter ORF is repressed by p53 uORF‐translation in cis, (2) p53 uORF‐containing mRNA is specifically degraded by a cellular mechanism dependent on uORF‐translation and PI3‐like kinase activity, and (3) the uORF in p53 mRNA encodes a peptide that is translatable in vitro and in human cells. Quantitative RT‐PCR of endogenous p53 mRNA species from cells treated with cycloheximide or caffeine indicate that uORF‐containing p53 mRNA is specifically increased in treated cells. Because the p53 uORF‐containing mRNA is rescued from degradation by chemical inhibition of translation and PI3‐like kinase activity, uORF‐translation induced NMD is implicated. Lastly, the p53 uORF‐encoded 23‐residue peptide (p53uORF23) was expressed as a C‐terminal fusion protein both in vitro & transfected human cells, immunoprecipitated, and identified by Western analyses. Collectively, these data are consistent with uORF‐translation induced NMD and uORF‐dependent translational repression of uORF‐containing p53mRNA.