Regulatory Role of Small Nucleolar RNAs in Human Diseases

Stepanov, Grigory A.; Filippova, Julia A.; Komissarov, Andrey B.; Kuligina, Elena V.; Richter, Vladimir A.; Semenov, Dmitry V.

It has been shown that numerous box C/D and box H/ACA RNAs have no identified targets among rRNAs or snRNAs. Such snoRNAs, referred to as "orphan snoR-NAs/scaRNAs, " may have some other regulatory function aside from 2 -O-methylation and pseudouridylation of RNA nucleotides [11] [12] [13] . Series of studies of snoRNA expression profiles in mammalian cells have demonstrated that the level of many "orphan" box C/D and box H/ACA RNAs varies among different tissues [14] [15] [16] [17] . The variation of snoRNA expression profiles suggests that such RNAs have tissue-specific functions. For example, two brain-specific box C/D RNAs SNORD115 (HBII-52) and SNORD116 (HBII-85) were shown to be processed into smaller RNAs that can affect the outcome of alternative splicing of various pre-mRNAs by preventing the formation of particular pre-mRNA splicing variants [18] . SNORD115 is also involved in the regulation of serotonin receptor 5-HT2CR mRNA level in brain cells through alternative splicing and control of posttranscriptional nucleotide modification (adenosine-toinosine editing) of the target mRNA [19, 20] .