Processing of snoRNAs as a new source of regulatory non-coding RNAs

snoRNA fragments form a new class of functional RNAs

Authors

  • Marina Falaleeva,

    1. Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, KY, USA
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  • Stefan Stamm

    Corresponding author
    1. Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, KY, USA
    • Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, KY, USA.
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Abstract

Recent experimental evidence suggests that most of the genome is transcribed into non-coding RNAs. The initial transcripts undergo further processing generating shorter, metabolically stable RNAs with diverse functions. Small nucleolar RNAs (snoRNAs) are non-coding RNAs that modify rRNAs, tRNAs, and snRNAs that were considered stable. We review evidence that snoRNAs undergo further processing. High-throughput sequencing and RNase protection experiments showed widespread expression of snoRNA fragments, known as snoRNA-derived RNAs (sdRNAs). Some sdRNAs resemble miRNAs, these can associate with argonaute proteins and influence translation. Other sdRNAs are longer, form complexes with hnRNPs and influence gene expression. C/D box snoRNA fragmentation patterns are conserved across multiple cell types, suggesting a processing event, rather than degradation. The loss of expression from genetic loci that generate canonical snoRNAs and processed snoRNAs results in diseases, such as Prader-Willi Syndrome, indicating possible physiological roles for processed snoRNAs. We propose that processed snoRNAs acquire new roles in gene expression and represent a new class of regulatory RNAs distinct from canonical snoRNAs.

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