Department of Biology, Baylor University Waco, TX, USA.
School of Biological Sciences, University of Nebraska-Lincoln Lincoln, NE, USA.
Front Mol Biosci. 2014 Dec 8;1:25. doi: 10.3389/fmolb.2014.00025. eCollection 2014.
The nonsense-mediated mRNA decay (NMD) pathway is a specialized pathway that triggers the rapid degradation of select mRNAs. Initially, identified as a pathway that degrades mRNAs with premature termination codons, NMD is now recognized as a pathway that also regulates some natural mRNAs. Since natural mRNAs do not typically contain premature termination codons, these mRNAs contain features that target them to NMD. In Saccharomyces cerevisiae mRNAs with atypically long 3'-UTRs are usually degraded by NMD, however in some conditions a constitutively expressed SSY5 mRNA with multiple NMD targeting signals including an atypically long 3'-UTR is an exception. We investigated the features of the SSY5 mRNAs that confer immunity to NMD. We found that the SSY5 mRNA 3'-UTRs are sufficient to target NMD insensitive mRNA to the pathway. Replacing the SSY5 3'-UTRs with the cyc1-512 3'-UTRs, known to target mRNAs to NMD or with the CYC1 3'-UTR, known not to target mRNAs to NMD, resulted in production of SSY5 mRNAs that were regulated by NMD. These observations suggest that the SSY5 mRNAs require sequences both within the 5'-UTR and/or ORF as well as the 3'-UTR to escape decay by NMD.
无意义介导的 mRNA 降解 (NMD) 途径是一种专门的途径，可触发特定 mRNA 的快速降解。最初，该途径被鉴定为降解具有过早终止密码子的 mRNA 的途径，现在被认为是一种还可以调节一些天然 mRNA 的途径。由于天然 mRNA 通常不含过早终止密码子，因此这些 mRNA 具有将其靶向 NMD 的特征。在酿酒酵母中，具有非典型长 3'-UTR 的 mRNAs 通常被 NMD 降解，但是在某些条件下，具有多个 NMD 靶向信号（包括非典型长 3'-UTR）的组成型表达的 SSY5 mRNA 是一个例外。我们研究了赋予 SSY5 mRNA 对 NMD 免疫的特征。我们发现，SSY5 mRNA 3'-UTRs 足以将对 NMD 不敏感的 mRNA 靶向该途径。用已知靶向 NMD 的 cyc1-512 3'-UTRs 或已知不靶向 NMD 的 CYC1 3'-UTR 替换 SSY5 3'-UTRs，会导致 SSY5 mRNAs 的产生受 NMD 调节。这些观察结果表明，SSY5 mRNAs 需要 5'-UTR 和/或 ORF 内以及 3'-UTR 内的序列才能逃避 NMD 的降解。
