Preferential translation of p53 target genes

Area of Science:

• Molecular Biology
• Cancer Research
• Gene Regulation

Background:

• The tumor suppressor p53 regulates gene expression transcriptionally.
• p53 also influences mRNA translation, but distinguishing active regulation from passive mRNA level changes is challenging.
• DNA damage activates p53, impacting cellular processes like cell cycle arrest and apoptosis.

Purpose of the Study:

• To comprehensively analyze translational regulation by p53.
• To differentiate active translational control from passive mRNA abundance changes.
• To identify specific mRNAs translationally regulated by p53 activation.

Main Methods:

• Comparative analysis of mRNA levels and ribosome densities in wild-type and TP53 knockout HCT116 cells after DNA damage (neocarzinostatin).
• Analysis of translational efficiency by correlating mRNA abundance with ribosome occupancy.
• Polysome profile analysis of specific p53 target genes (SESN1, CDKN1A).

Main Results:

• Identified a specific set of mRNAs preferentially translated upon p53 activation.
• Found that p53 target genes, including MDM2, SESN1, and CDKN1A, are among those translationally upregulated.
• Demonstrated that p53-dependent translational activation involves both the induction of advantageous mRNA isoforms and trans-acting mechanisms.

Conclusions:

• p53 actively and specifically enhances the translation of a subset of its target mRNAs.
• This translational control mechanism is crucial for p53's tumor suppressive functions.
• p53 utilizes multiple strategies, including isoform selection and trans-acting factors, to boost translation efficiency of key genes.