Hindawi Publishing Corporation BioMed Research International Volume 2013, Article ID 656158, 9 pages http://dx.doi.org/10.1155/2013/656158 Research Article Artificial Box C/D RNAs Affect Pre-mRNA Maturation in Human Cells Grigoriy A. Stepanov, Dmitry V. Semenov, Anna V. Savelyeva, Elena V. Kuligina, Olga A. Koval, Igor V. Rabinov, and Vladimir A. Richter Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences, Lavrentiev Avenue 8, Novosibirsk 630090, Russia Correspondence should be addressed to Grigoriy A. Stepanov; stepanovga@niboch.nsc.ru Received 31 October 2012; Revised 27 January 2013; Accepted 9 February 2013 Academic Editor: Yasushi Okazaki Copyright © 2013 Grigoriy A. Stepanov et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Box C/D small nucleolar RNAs (snoRNAs) are known to guide the 2  -O-ribose methylation of nucleotides in eukaryotic ribosomal RNAs and small nuclear RNAs. Recently snoRNAs are predicted to regulate posttranscriptional modiications of pre-mRNA. To expand understanding of the role of snoRNAs in control of gene expression, in this study we tested the ability of artiicial box C/D RNAs to afect the maturation of target pre-mRNA. We found that transfection of artiicial box C/D snoRNA analogues directed to HSPA8 pre-mRNAs into human cells induced suppression of the target mRNA expression in a time- and dose-dependent manner. he artiicial box C/D RNA directed to the branch point adenosine of the second intron, as well as the analogue directed to the last nucleotide of the second exon of the HSPA8 pre-mRNA caused the most prominent inluence on the level of HSPA8 mRNAs. Neither box D nor the ability to direct 2  -O-methylation of nucleotides in target RNA was essential for the knockdown activity of artiicial snoRNAs. Inasmuch as artiicial box C/D RNAs decreased viability of transfected human cells, we propose that natural snoRNAs as well as their artiicial analogues can inluence the maturation of complementary pre-mRNA and can be efective regulators of vital cellular processes. 1. Introduction Small nucleolar RNAs (snoRNA) are commonly known to be involved in the processing of precursor ribosomal RNA (pre-rRNA) and small nuclear RNAs (snRNAs). Box C/D snoRNAs direct 2  -O-methylation of rRNA nucleotides, and box H/ACA snoRNAs guide the conversion of uridine to pseudouridine [1–4]. he snoRNA-dependent modiications are catalyzed by small nucleolar ribonucleoprotein particles (snoRNPs). Box C/D RNAs are associated with four snoRNP core proteins: NOP56, NOP58, ibrillarin, and 15.5 kDa [5–7]. Box C/D RNAs contain the following functional ele- ments: boxes C and D, which are essential for snoRNA interaction with speciic proteins, and a guide sequence that determines the nucleotide to be modiied (Figure 1(a)). Some box C/D snoRNAs involve a second pair of boxes C/D, named C  and D  , within the snoRNA molecule. In that case, snoRNAs hold two potential guide sequences [2, 4]. rRNAs and snRNAs are the main natural targets of 2  -O- methylation that is mediated by box C/D RNAs. However, a number of snoRNA-like transcripts do not have guide sequences that are complementary to rRNA or snRNA, so they have unknown functions and are called “orphan snoRNAs” [8, 9]. Bioinformatics analysis revealed that some of these orphan RNAs were complementary to pre-mRNAs or mature mRNAs [10]. MBII-52 box C/D snoRNA containing a guide sequence complementary to the serotonin receptor 2C pre-mRNA was reported to take part in controlling the posttranscriptional modiication of the target pre-mRNA (conversion A to I) [11]. It was also shown that HBII-52 snoRNA could regulate alternative splicing of the comple- mentary pre-mRNA [12].