PABP stabilizes select mRNAs populations in human cells

Gene expression is tightly regulated at the levels of both mRNA translation and stability. The poly(A) binding protein (PABP) plays a role in regulating these processes by binding the mRNA 3´ poly(A) tail and interfacing with both the translation initiation and mRNA deadenylation machineries. Here we directly investigate the impact of PABP on the translation and stability of endogenous mRNAs in human cell lines. Remarkably, our transcriptome-wide analysis does not generally detect changes to mRNA translation in PABP-depleted cells. In contrast, rapidly depleting PABP alters transcriptome abundance and stability, albeit non-uniformly. Transcripts with long half-lives and short 3’UTRs are preferentially depleted in PABP-depleted cells. PABP depletion induces cell death; however, disrupting the mRNA decapping and 5’-3’ decay machinery can partially suppress this lethality. Finally, we show that disrupting the LSM1-7 complex prevents the premature decay of mRNAs that are destabilized in PABP-depleted cells. Taken together, these findings suggest that PABP plays an important role in preventing the untimely decay of select mRNA populations in human cells. 3 biological replicates of PABPC1DHFR HeLa cells cultured in the presence or absence of TMP.