Figure 2. Coupling of RNA processing to alternative RNA regulation.

A. Alternative polyadenylation can generate mRNAs with common and isoform-specific 3′ UTR sequences. Changes in 3′ UTR length can alter the repertoire of regulatory elements present in the UTR, such as miRNA target sequences, thus affecting the ability of the transcript to be subject to different forms of post-transcriptional regulation, in this case mRNA degradation. B. Alternative splicing can lead to coding frameshifts, resulting in the introduction of premature translation termination codon (PTC). The presence of a PTC triggers degradation of the mRNA by the NMD pathway, thus regulation of alternative pre-mRNA splicing can be used to control transcript abundance, as evidenced in the physiologic regulation of the RNABPs Ptbp1 and Ptbp2¹¹⁰–¹¹²,¹²².