Functions of Long Non-Coding RNAs in Non-mammalian Systems
Transcription of eukaryotic genomes is pervasive, with most if not all bases transcribed. A single stretch of genomic sequence is commonly represented in numerous distinct transcripts, due to the use of alternative transcription start and termination sites, the ability of RNA polymerase II (Pol II) to transcribe in either orientation or alternative RNA processing events. The transcriptome is thus overwhelmingly complex and contains many so-called long non-coding RNAs (lncRNAs), which lack protein coding capacity. These are distinct from classically annotated classes of structural RNAs (e.g. rRNA, tRNA, snRNA, snoRNA), or the more recently discovered small regulatory RNAs (siRNA, miRNA and piRNA). In this chapter, we focus on recent advances toward understanding the functions of lncRNAs in non-mammalian systems including yeast, plants and flies. The amenability of these organisms to genetic manipulation and their short generation time has enabled rapid progress to be made, often at the mechanistic level. In mammalian cells, there is extensive crosstalk between lncRNAs and small (~21–25 nt) regulatory RNAs. However, these very small RNAs are apparently absent from the yeast Saccharomyces cerevisiae, while lncRNAs and small regulatory RNAs in Arabidopsis are transcribed by distinct, specialized polymerases. Studies in these organisms have helped define the individual contributions of lncRNAs and small RNAs, and reveal how they collaborate and compete in RNA-dependent regulatory pathways.
KeywordsTranscription Start Site Transcriptional Gene Silence Histone Chaperone Upstream Activate Sequence Nascent Transcript
This work was funded by Wellcome Trust [086587 and 077248]. Work in the Wellcome Trust Centre for Cell Biology is supported by Wellcome Trust core funding .
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