Tumor suppressor protein Pdcd4 inhibits translation of p53 mRNA.
The tumor suppressor protein Pdcd4 is thought to suppress translation of mRNAs containing structured 5'-UTRs by interacting with translation initiation factor eIF4A and inhibiting its helicase activity. However, natural target mRNAs regulated by Pdcd4 so far are mostly unknown. Here, we identified p53 mRNA as a translational target of Pdcd4. We found that Pdcd4 is associated with p53 mRNA and suppresses its translation. The inhibitory effect of Pdcd4 on the translation of p53 mRNA depends on the ability of Pdcd4 to interact with eIF4A and is mediated by the 5'-UTR of p53 mRNA, which is able to form a stable stem-loop structure. We show that treatment of cells with DNA-damaging agents decreases the expression of Pdcd4. This suggests that translational suppression by Pdcd4 plays a role in maintaining a low level of p53 in unstressed cells and that this suppression is abrogated due to low levels of Pdcd4 after DNA damage. Overall, our work demonstrates for the first time that Pdcd4 is directly involved in translational suppression of a natural mRNA with a 5'-structured UTR and provides novel insight into the translational control of p53 expression.
Institut für Biochemie, Westfälische-Wilhelms-Universität Münster, D-48149 Münster, Germany.
Lena
L
Wedeken
Priyanka
P
Singh
Karl-Heinz
KH
Klempnauer
D020121:5' Untranslated Regions / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D039642:Eukaryotic Initiation Factors / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D011485:Protein Binding; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism*
D020121:5' Untranslated Regions; D051017:Apoptosis Regulatory Proteins; D039642:Eukaryotic Initiation Factors; C114487:PDCD4 protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D016159:Tumor Suppressor Protein p53